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Last updated: Sat Feb 3 05:00:42 2007

Asterisk developer's documentation :: Codename Pineapple

---

chan_zap.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Zaptel Pseudo TDM interface 
 *
 * \author Mark Spencer <markster@digium.com>
 * 
 * Connects to the zaptel telephony library as well as 
 * libpri. Libpri is optional and needed only if you are
 * going to use ISDN connections.
 *
 * You need to install libraries before you attempt to compile
 * and install the zaptel channel.
 *
 * \par See also
 * \arg \ref Config_zap
 *
 * \ingroup channel_drivers
 *
 * \todo Deprecate the "musiconhold" configuration option post 1.4
 */

/*** MODULEINFO
   <depend>zaptel_vldtmf</depend>
   <depend>zaptel</depend>
   <depend>tonezone</depend>
   <use>pri</use>
   <use>ss7</use>
 ***/

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 51806 $")

#include <stdio.h>
#include <string.h>
#ifdef __NetBSD__
#include <pthread.h>
#include <signal.h>
#else
#include <sys/signal.h>
#endif
#include <errno.h>
#include <stdlib.h>
#if !defined(SOLARIS) && !defined(__FreeBSD__)
#include <stdint.h>
#endif
#include <unistd.h>
#include <sys/ioctl.h>
#include <math.h>
#include <ctype.h>
#include "asterisk/zapata.h"

#ifdef HAVE_PRI
#include <libpri.h>
#endif

#ifdef HAVE_SS7
#include <libss7.h>
#endif

#include "asterisk/lock.h"
#include "asterisk/channel.h"
#include "asterisk/config.h"
#include "asterisk/logger.h"
#include "asterisk/module.h"
#include "asterisk/pbx.h"
#include "asterisk/options.h"
#include "asterisk/file.h"
#include "asterisk/ulaw.h"
#include "asterisk/alaw.h"
#include "asterisk/callerid.h"
#include "asterisk/adsi.h"
#include "asterisk/cli.h"
#include "asterisk/cdr.h"
#include "asterisk/features.h"
#include "asterisk/musiconhold.h"
#include "asterisk/say.h"
#include "asterisk/tdd.h"
#include "asterisk/app.h"
#include "asterisk/dsp.h"
#include "asterisk/astdb.h"
#include "asterisk/manager.h"
#include "asterisk/causes.h"
#include "asterisk/term.h"
#include "asterisk/utils.h"
#include "asterisk/transcap.h"
#include "asterisk/stringfields.h"
#include "asterisk/abstract_jb.h"
#include "asterisk/smdi.h"
#include "asterisk/astobj.h"
#define SMDI_MD_WAIT_TIMEOUT 1500 /* 1.5 seconds */

/*! Global jitterbuffer configuration - by default, jb is disabled */
static struct ast_jb_conf default_jbconf =
{
   .flags = 0,
   .max_size = -1,
   .resync_threshold = -1,
   .impl = ""
};
static struct ast_jb_conf global_jbconf;

#if !defined(ZT_SIG_EM_E1) || (defined(HAVE_PRI) && !defined(ZT_SIG_HARDHDLC))
#error "Your zaptel is too old.  Please update"
#endif

#ifndef ZT_TONEDETECT
/* Work around older code with no tone detect */
#define ZT_EVENT_DTMFDOWN 0
#define ZT_EVENT_DTMFUP 0
#endif

/* define this to send PRI user-user information elements */
#undef SUPPORT_USERUSER

/*! 
 * \note Define ZHONE_HACK to cause us to go off hook and then back on hook when
 * the user hangs up to reset the state machine so ring works properly.
 * This is used to be able to support kewlstart by putting the zhone in
 * groundstart mode since their forward disconnect supervision is entirely
 * broken even though their documentation says it isn't and their support
 * is entirely unwilling to provide any assistance with their channel banks
 * even though their web site says they support their products for life.
 */
/* #define ZHONE_HACK */

/*! \note
 * Define if you want to check the hook state for an FXO (FXS signalled) interface
 * before dialing on it.  Certain FXO interfaces always think they're out of
 * service with this method however.
 */
/* #define ZAP_CHECK_HOOKSTATE */

/*! \brief Typically, how many rings before we should send Caller*ID */
#define DEFAULT_CIDRINGS 1

#define CHANNEL_PSEUDO -12

#define AST_LAW(p) (((p)->law == ZT_LAW_ALAW) ? AST_FORMAT_ALAW : AST_FORMAT_ULAW)

/*! \brief Signaling types that need to use MF detection should be placed in this macro */
#define NEED_MFDETECT(p) (((p)->sig == SIG_FEATDMF) || ((p)->sig == SIG_FEATDMF_TA) || ((p)->sig == SIG_E911) || ((p)->sig == SIG_FGC_CAMA) || ((p)->sig == SIG_FGC_CAMAMF) || ((p)->sig == SIG_FEATB)) 

static const char tdesc[] = "Zapata Telephony Driver"
#ifdef HAVE_PRI
               " w/PRI"
#endif
#ifdef HAVEL_LIBSS7
          "w/SS7"
#endif
;

static const char config[] = "zapata.conf";

#define SIG_EM    ZT_SIG_EM
#define SIG_EMWINK   (0x0100000 | ZT_SIG_EM)
#define SIG_FEATD (0x0200000 | ZT_SIG_EM)
#define  SIG_FEATDMF (0x0400000 | ZT_SIG_EM)
#define  SIG_FEATB   (0x0800000 | ZT_SIG_EM)
#define  SIG_E911 (0x1000000 | ZT_SIG_EM)
#define  SIG_FEATDMF_TA (0x2000000 | ZT_SIG_EM)
#define  SIG_FGC_CAMA   (0x4000000 | ZT_SIG_EM)
#define  SIG_FGC_CAMAMF (0x8000000 | ZT_SIG_EM)
#define SIG_FXSLS ZT_SIG_FXSLS
#define SIG_FXSGS ZT_SIG_FXSGS
#define SIG_FXSKS ZT_SIG_FXSKS
#define SIG_FXOLS ZT_SIG_FXOLS
#define SIG_FXOGS ZT_SIG_FXOGS
#define SIG_FXOKS ZT_SIG_FXOKS
#define SIG_PRI      ZT_SIG_CLEAR
#define SIG_SS7      (0x1000000 | ZT_SIG_CLEAR)
#define  SIG_SF      ZT_SIG_SF
#define SIG_SFWINK   (0x0100000 | ZT_SIG_SF)
#define SIG_SF_FEATD (0x0200000 | ZT_SIG_SF)
#define  SIG_SF_FEATDMF (0x0400000 | ZT_SIG_SF)
#define  SIG_SF_FEATB   (0x0800000 | ZT_SIG_SF)
#define SIG_EM_E1 ZT_SIG_EM_E1
#define SIG_GR303FXOKS  (0x0100000 | ZT_SIG_FXOKS)
#define SIG_GR303FXSKS  (0x0100000 | ZT_SIG_FXSKS)

#define NUM_SPANS       32
#define NUM_DCHANS      4  /*!< No more than 4 d-channels */
#define MAX_CHANNELS 672      /*!< No more than a DS3 per trunk group */

#define CHAN_PSEUDO  -2

#define DCHAN_PROVISIONED (1 << 0)
#define DCHAN_NOTINALARM  (1 << 1)
#define DCHAN_UP          (1 << 2)

#define DCHAN_AVAILABLE (DCHAN_PROVISIONED | DCHAN_NOTINALARM | DCHAN_UP)

static char defaultcic[64] = "";
static char defaultozz[64] = "";

static char language[MAX_LANGUAGE] = "";
static char progzone[10] = "";

static int usedistinctiveringdetection = 0;
static int distinctiveringaftercid = 0;

static int numbufs = 4;

#ifdef HAVE_PRI
static struct ast_channel inuse;
#ifdef PRI_GETSET_TIMERS
static int pritimers[PRI_MAX_TIMERS];
#endif
static int pridebugfd = -1;
static char pridebugfilename[1024] = "";
#endif

/*! \brief Wait up to 16 seconds for first digit (FXO logic) */
static int firstdigittimeout = 16000;

/*! \brief How long to wait for following digits (FXO logic) */
static int gendigittimeout = 8000;

/*! \brief How long to wait for an extra digit, if there is an ambiguous match */
static int matchdigittimeout = 3000;

/*! \brief Protect the interface list (of zt_pvt's) */
AST_MUTEX_DEFINE_STATIC(iflock);


static int ifcount = 0;

#ifdef HAVE_PRI
AST_MUTEX_DEFINE_STATIC(pridebugfdlock);
#endif

/*! \brief Protect the monitoring thread, so only one process can kill or start it, and not
   when it's doing something critical. */
AST_MUTEX_DEFINE_STATIC(monlock);

/*! \brief This is the thread for the monitor which checks for input on the channels
   which are not currently in use. */
static pthread_t monitor_thread = AST_PTHREADT_NULL;

static int restart_monitor(void);

static enum ast_bridge_result zt_bridge(struct ast_channel *c0, struct ast_channel *c1, int flags, struct ast_frame **fo, struct ast_channel **rc, int timeoutms);

static int zt_sendtext(struct ast_channel *c, const char *text);

/*! \brief Avoid the silly zt_getevent which ignores a bunch of events */
static inline int zt_get_event(int fd)
{
   int j;
   if (ioctl(fd, ZT_GETEVENT, &j) == -1)
      return -1;
   return j;
}

/*! \brief Avoid the silly zt_waitevent which ignores a bunch of events */
static inline int zt_wait_event(int fd)
{
   int i, j = 0;
   i = ZT_IOMUX_SIGEVENT;
   if (ioctl(fd, ZT_IOMUX, &i) == -1)
      return -1;
   if (ioctl(fd, ZT_GETEVENT, &j) == -1)
      return -1;
   return j;
}

/*! Chunk size to read -- we use 20ms chunks to make things happy. */
#define READ_SIZE 160

#define MASK_AVAIL      (1 << 0) /*!< Channel available for PRI use */
#define MASK_INUSE      (1 << 1) /*!< Channel currently in use */

#define CALLWAITING_SILENT_SAMPLES  ( (300 * 8) / READ_SIZE) /*!< 300 ms */
#define CALLWAITING_REPEAT_SAMPLES  ( (10000 * 8) / READ_SIZE) /*!< 300 ms */
#define CIDCW_EXPIRE_SAMPLES     ( (500 * 8) / READ_SIZE) /*!< 500 ms */
#define MIN_MS_SINCE_FLASH       ( (2000) )  /*!< 2000 ms */
#define DEFAULT_RINGT            ( (8000 * 8) / READ_SIZE)

struct zt_pvt;

static int ringt_base = DEFAULT_RINGT;

#ifdef HAVE_SS7

#define LINKSTATE_INALARM  (1 << 0)
#define LINKSTATE_STARTING (1 << 1)
#define LINKSTATE_UP    (1 << 2)
#define LINKSTATE_DOWN     (1 << 3)

struct zt_ss7 {
   pthread_t master;                /*!< Thread of master */
   ast_mutex_t lock;
   int fds[NUM_DCHANS];
   int numsigchans;
   int linkstate[NUM_DCHANS];
   int numchans;
   int type;
   enum {
      LINKSET_STATE_DOWN = 0,
      LINKSET_STATE_UP
   } state;
   struct ss7 *ss7;
   struct zt_pvt *pvts[MAX_CHANNELS];           /*!< Member channel pvt structs */
};

static struct zt_ss7 linksets[NUM_SPANS];

static int cur_ss7type = -1;
static int cur_linkset = -1;
static int cur_pointcode = -1;
static int cur_cicbeginswith = -1;
static int cur_adjpointcode = -1;
static int cur_networkindicator = -1;
static int cur_defaultdpc = -1;
#endif /* HAVE_SS7 */

#ifdef HAVE_PRI

#define PVT_TO_CHANNEL(p) (((p)->prioffset) | ((p)->logicalspan << 8) | (p->pri->mastertrunkgroup ? 0x10000 : 0))
#define PRI_CHANNEL(p) ((p) & 0xff)
#define PRI_SPAN(p) (((p) >> 8) & 0xff)
#define PRI_EXPLICIT(p) (((p) >> 16) & 0x01)

struct zt_pri {
   pthread_t master;                /*!< Thread of master */
   ast_mutex_t lock;                /*!< Mutex */
   char idleext[AST_MAX_EXTENSION];          /*!< Where to idle extra calls */
   char idlecontext[AST_MAX_CONTEXT];           /*!< What context to use for idle */
   char idledial[AST_MAX_EXTENSION];            /*!< What to dial before dumping */
   int minunused;                   /*!< Min # of channels to keep empty */
   int minidle;                     /*!< Min # of "idling" calls to keep active */
   int nodetype;                    /*!< Node type */
   int switchtype;                     /*!< Type of switch to emulate */
   int nsf;                   /*!< Network-Specific Facilities */
   int dialplan;                    /*!< Dialing plan */
   int localdialplan;                  /*!< Local dialing plan */
   char internationalprefix[10];             /*!< country access code ('00' for european dialplans) */
   char nationalprefix[10];               /*!< area access code ('0' for european dialplans) */
   char localprefix[20];                  /*!< area access code + area code ('0'+area code for european dialplans) */
   char privateprefix[20];                /*!< for private dialplans */
   char unknownprefix[20];                /*!< for unknown dialplans */
   int dchannels[NUM_DCHANS];             /*!< What channel are the dchannels on */
   int trunkgroup;                     /*!< What our trunkgroup is */
   int mastertrunkgroup;                  /*!< What trunk group is our master */
   int prilogicalspan;                 /*!< Logical span number within trunk group */
   int numchans;                    /*!< Num of channels we represent */
   int overlapdial;                 /*!< In overlap dialing mode */
   int facilityenable;                 /*!< Enable facility IEs */
   struct pri *dchans[NUM_DCHANS];              /*!< Actual d-channels */
   int dchanavail[NUM_DCHANS];               /*!< Whether each channel is available */
   struct pri *pri;                 /*!< Currently active D-channel */
   int debug;
   int fds[NUM_DCHANS];                /*!< FD's for d-channels */
   int offset;
   int span;
   int resetting;
   int resetpos;
   time_t lastreset;                /*!< time when unused channels were last reset */
   long resetinterval;                 /*!< Interval (in seconds) for resetting unused channels */
   struct zt_pvt *pvts[MAX_CHANNELS];           /*!< Member channel pvt structs */
   struct zt_pvt *crvs;                /*!< Member CRV structs */
   struct zt_pvt *crvend;                 /*!< Pointer to end of CRV structs */
};


static struct zt_pri pris[NUM_SPANS];

#if 0
#define DEFAULT_PRI_DEBUG (PRI_DEBUG_Q931_DUMP | PRI_DEBUG_Q921_DUMP | PRI_DEBUG_Q921_RAW | PRI_DEBUG_Q921_STATE)
#else
#define DEFAULT_PRI_DEBUG 0
#endif

static inline void pri_rel(struct zt_pri *pri)
{
   ast_mutex_unlock(&pri->lock);
}

#else
/*! Shut up the compiler */
struct zt_pri;
#endif

#define SUB_REAL  0        /*!< Active call */
#define SUB_CALLWAIT 1        /*!< Call-Waiting call on hold */
#define SUB_THREEWAY 2        /*!< Three-way call */

/* Polarity states */
#define POLARITY_IDLE   0
#define POLARITY_REV    1


static struct zt_distRings drings;

struct distRingData {
   int ring[3];
   int range;
};
struct ringContextData {
   char contextData[AST_MAX_CONTEXT];
};
struct zt_distRings {
   struct distRingData ringnum[3];
   struct ringContextData ringContext[3];
};

static char *subnames[] = {
   "Real",
   "Callwait",
   "Threeway"
};

struct zt_subchannel {
   int zfd;
   struct ast_channel *owner;
   int chan;
   short buffer[AST_FRIENDLY_OFFSET/2 + READ_SIZE];
   struct ast_frame f;     /*!< One frame for each channel.  How did this ever work before? */
   unsigned int needringing:1;
   unsigned int needbusy:1;
   unsigned int needcongestion:1;
   unsigned int needcallerid:1;
   unsigned int needanswer:1;
   unsigned int needflash:1;
   unsigned int needhold:1;
   unsigned int needunhold:1;
   unsigned int linear:1;
   unsigned int inthreeway:1;
   ZT_CONFINFO curconf;
};

#define CONF_USER_REAL     (1 << 0)
#define CONF_USER_THIRDCALL   (1 << 1)

#define MAX_SLAVES   4

static struct zt_pvt {
   ast_mutex_t lock;
   struct ast_channel *owner;       /*!< Our current active owner (if applicable) */
                     /*!< Up to three channels can be associated with this call */
      
   struct zt_subchannel sub_unused;    /*!< Just a safety precaution */
   struct zt_subchannel subs[3];       /*!< Sub-channels */
   struct zt_confinfo saveconf;        /*!< Saved conference info */

   struct zt_pvt *slaves[MAX_SLAVES];     /*!< Slave to us (follows our conferencing) */
   struct zt_pvt *master;           /*!< Master to us (we follow their conferencing) */
   int inconference;          /*!< If our real should be in the conference */
   
   int sig;             /*!< Signalling style */
   int radio;              /*!< radio type */
   int outsigmod;             /*!< Outbound Signalling style (modifier) */
   int oprmode;               /*!< "Operator Services" mode */
   struct zt_pvt *oprpeer;          /*!< "Operator Services" peer tech_pvt ptr */
   float rxgain;
   float txgain;
   int tonezone;              /*!< tone zone for this chan, or -1 for default */
   struct zt_pvt *next;          /*!< Next channel in list */
   struct zt_pvt *prev;          /*!< Prev channel in list */

   /* flags */
   unsigned int adsi:1;
   unsigned int answeronpolarityswitch:1;
   unsigned int busydetect:1;
   unsigned int callreturn:1;
   unsigned int callwaiting:1;
   unsigned int callwaitingcallerid:1;
   unsigned int cancallforward:1;
   unsigned int canpark:1;
   unsigned int confirmanswer:1;       /*!< Wait for '#' to confirm answer */
   unsigned int destroy:1;
   unsigned int didtdd:1;           /*!< flag to say its done it once */
   unsigned int dialednone:1;
   unsigned int dialing:1;
   unsigned int digital:1;
   unsigned int dnd:1;
   unsigned int echobreak:1;
   unsigned int echocanbridged:1;
   unsigned int echocanon:1;
   unsigned int faxhandled:1;       /*!< Has a fax tone already been handled? */
   unsigned int firstradio:1;
   unsigned int hanguponpolarityswitch:1;
   unsigned int hardwaredtmf:1;
   unsigned int hidecallerid:1;
   unsigned int hidecalleridname:1;      /*!< Hide just the name not the number for legacy PBX use */
   unsigned int ignoredtmf:1;
   unsigned int immediate:1;        /*!< Answer before getting digits? */
   unsigned int inalarm:1;
   unsigned int mate:1;          /*!< flag to say its in MATE mode */
   unsigned int outgoing:1;
   unsigned int overlapdial:1;
   unsigned int permcallwaiting:1;
   unsigned int permhidecallerid:1;    /*!< Whether to hide our outgoing caller ID or not */
   unsigned int priindication_oob:1;
   unsigned int priexclusive:1;
   unsigned int pulse:1;
   unsigned int pulsedial:1;        /*!< whether a pulse dial phone is detected */
   unsigned int restrictcid:1;         /*!< Whether restrict the callerid -> only send ANI */
   unsigned int threewaycalling:1;
   unsigned int transfer:1;
   unsigned int use_callerid:1;        /*!< Whether or not to use caller id on this channel */
   unsigned int use_callingpres:1;        /*!< Whether to use the callingpres the calling switch sends */
   unsigned int usedistinctiveringdetection:1;
   unsigned int zaptrcallerid:1;       /*!< should we use the callerid from incoming call on zap transfer or not */
   unsigned int transfertobusy:1;         /*!< allow flash-transfers to busy channels */
   /* Channel state or unavilability flags */
   unsigned int inservice:1;
   unsigned int locallyblocked:1;
   unsigned int remotelyblocked:1;
#if defined(HAVE_PRI)
   unsigned int alerting:1;
   unsigned int alreadyhungup:1;
   unsigned int isidlecall:1;
   unsigned int proceeding:1;
   unsigned int progress:1;
   unsigned int resetting:1;
   unsigned int setup_ack:1;
#endif
   unsigned int use_smdi:1;      /* Whether to use SMDI on this channel */
   struct ast_smdi_interface *smdi_iface; /* The serial port to listen for SMDI data on */

   struct zt_distRings drings;

   char context[AST_MAX_CONTEXT];
   char defcontext[AST_MAX_CONTEXT];
   char exten[AST_MAX_EXTENSION];
   char language[MAX_LANGUAGE];
   char mohinterpret[MAX_MUSICCLASS];
   char mohsuggest[MAX_MUSICCLASS];
#ifdef PRI_ANI
   char cid_ani[AST_MAX_EXTENSION];
#endif
   char cid_num[AST_MAX_EXTENSION];
   int cid_ton;               /*!< Type Of Number (TON) */
   char cid_name[AST_MAX_EXTENSION];
   char lastcid_num[AST_MAX_EXTENSION];
   char lastcid_name[AST_MAX_EXTENSION];
   char *origcid_num;            /*!< malloced original callerid */
   char *origcid_name;           /*!< malloced original callerid */
   char callwait_num[AST_MAX_EXTENSION];
   char callwait_name[AST_MAX_EXTENSION];
   char rdnis[AST_MAX_EXTENSION];
   char dnid[AST_MAX_EXTENSION];
   unsigned int group;
   int law;
   int confno;             /*!< Our conference */
   int confusers;             /*!< Who is using our conference */
   int propconfno;               /*!< Propagated conference number */
   ast_group_t callgroup;
   ast_group_t pickupgroup;
   int channel;               /*!< Channel Number or CRV */
   int span;               /*!< Span number */
   time_t guardtime;          /*!< Must wait this much time before using for new call */
   int cid_signalling;           /*!< CID signalling type bell202 or v23 */
   int cid_start;             /*!< CID start indicator, polarity or ring */
   int callingpres;           /*!< The value of callling presentation that we're going to use when placing a PRI call */
   int callwaitingrepeat;           /*!< How many samples to wait before repeating call waiting */
   int cidcwexpire;           /*!< When to expire our muting for CID/CW */
   unsigned char *cidspill;
   int cidpos;
   int cidlen;
   int ringt;
   int ringt_base;
   int stripmsd;
   int callwaitcas;
   int callwaitrings;
   int echocancel;
   int echotraining;
   char echorest[20];
   int busycount;
   int busy_tonelength;
   int busy_quietlength;
   int callprogress;
   struct timeval flashtime;        /*!< Last flash-hook time */
   struct ast_dsp *dsp;
   int cref;               /*!< Call reference number */
   ZT_DIAL_OPERATION dop;
   int whichwink;             /*!< SIG_FEATDMF_TA Which wink are we on? */
   char finaldial[64];
   char accountcode[AST_MAX_ACCOUNT_CODE];      /*!< Account code */
   int amaflags;              /*!< AMA Flags */
   struct tdd_state *tdd;           /*!< TDD flag */
   char call_forward[AST_MAX_EXTENSION];
   char mailbox[AST_MAX_EXTENSION];
   char dialdest[256];
   int onhooktime;
   int msgstate;
   int distinctivering;          /*!< Which distinctivering to use */
   int cidrings;              /*!< Which ring to deliver CID on */
   int dtmfrelax;             /*!< whether to run in relaxed DTMF mode */
   int fake_event;
   int polarityonanswerdelay;
   struct timeval polaritydelaytv;
   int sendcalleridafter;
#ifdef HAVE_PRI
   struct zt_pri *pri;
   struct zt_pvt *bearer;
   struct zt_pvt *realcall;
   q931_call *call;
   int prioffset;
   int logicalspan;
#endif   
   int polarity;
   int dsp_features;
#ifdef HAVE_SS7
   struct zt_ss7 *ss7;
   struct isup_call *ss7call;
   int transcap;
   int cic;                   /*!< CIC associated with channel */
#endif
   char begindigit;
} *iflist = NULL, *ifend = NULL;

/*! \brief Channel configuration from zapata.conf .
 * This struct is used for parsing the [channels] section of zapata.conf.
 * Generally there is a field here for every possible configuration item.
 *
 * The state of fields is saved along the parsing and whenever a 'channel'
 * statement is reached, the current zt_chan_conf is used to configure the 
 * channel (struct zt_pvt)
 *
 * @seealso zt_chan_init for the default values.
 */
struct zt_chan_conf {
   struct zt_pvt chan;
#ifdef HAVE_PRI
   struct zt_pri pri;
#endif
   ZT_PARAMS timing;

   char smdi_port[SMDI_MAX_FILENAME_LEN];
};

/** returns a new zt_chan_conf with default values (by-value) */
static struct zt_chan_conf zt_chan_conf_default(void) {
   /* recall that if a field is not included here it is initialized
    * to 0 or equivalent
    */
   struct zt_chan_conf conf = {
#ifdef HAVE_PRI
      .pri = {
         .nsf = PRI_NSF_NONE,
         .switchtype = PRI_SWITCH_NI2,
         .dialplan = PRI_NATIONAL_ISDN + 1,
         .localdialplan = PRI_NATIONAL_ISDN + 1,
         .nodetype = PRI_CPE,

         .minunused = 2,
         .idleext = "",
         .idledial = "",
         .internationalprefix = "",
         .nationalprefix = "",
         .localprefix = "",
         .privateprefix = "",
         .unknownprefix = "",

         .resetinterval = 3600
      },
#endif
      .chan = {
         .context = "default",
         .cid_num = "",
         .cid_name = "",
         .mohinterpret = "default",
         .mohsuggest = "",
         .transfertobusy = 1,

         .cid_signalling = CID_SIG_BELL,
         .cid_start = CID_START_RING,
         .zaptrcallerid = 0,
         .use_callerid = 1,
         .sig = -1,
         .outsigmod = -1,

         .tonezone = -1,

         .echocancel = 1,

         .busycount = 3,

         .accountcode = "",

         .mailbox = "",


         .polarityonanswerdelay = 600,

         .sendcalleridafter = DEFAULT_CIDRINGS
      },
      .timing = {
         .prewinktime = -1,
         .preflashtime = -1,
         .winktime = -1,
         .flashtime = -1,
         .starttime = -1,
         .rxwinktime = -1,
         .rxflashtime = -1,
         .debouncetime = -1
      },
      .smdi_port = "/dev/ttyS0",
   };

   return conf;
}


static struct ast_channel *zt_request(const char *type, int format, void *data, int *cause);
static int zt_digit_begin(struct ast_channel *ast, char digit);
static int zt_digit_end(struct ast_channel *ast, char digit, unsigned int duration);
static int zt_sendtext(struct ast_channel *c, const char *text);
static int zt_call(struct ast_channel *ast, char *rdest, int timeout);
static int zt_hangup(struct ast_channel *ast);
static int zt_answer(struct ast_channel *ast);
static struct ast_frame *zt_read(struct ast_channel *ast);
static int zt_write(struct ast_channel *ast, struct ast_frame *frame);
static struct ast_frame *zt_exception(struct ast_channel *ast);
static int zt_indicate(struct ast_channel *chan, int condition, const void *data, size_t datalen);
static int zt_fixup(struct ast_channel *oldchan, struct ast_channel *newchan);
static int zt_setoption(struct ast_channel *chan, int option, void *data, int datalen);
static int zt_func_read(struct ast_channel *chan, const char *function, char *data, char *buf, size_t len);

static const struct ast_channel_tech zap_tech = {
   .type = "Zap",
   .description = tdesc,
   .capabilities = AST_FORMAT_SLINEAR | AST_FORMAT_ULAW | AST_FORMAT_ALAW,
   .requester = zt_request,
   .send_digit_begin = zt_digit_begin,
   .send_digit_end = zt_digit_end,
   .send_text = zt_sendtext,
   .call = zt_call,
   .hangup = zt_hangup,
   .answer = zt_answer,
   .read = zt_read,
   .write = zt_write,
   .bridge = zt_bridge,
   .exception = zt_exception,
   .indicate = zt_indicate,
   .fixup = zt_fixup,
   .setoption = zt_setoption,
   .func_channel_read = zt_func_read,
};

#ifdef HAVE_PRI
#define GET_CHANNEL(p) ((p)->bearer ? (p)->bearer->channel : p->channel)
#else
#define GET_CHANNEL(p) ((p)->channel)
#endif

struct zt_pvt *round_robin[32];

#ifdef HAVE_PRI
static inline int pri_grab(struct zt_pvt *pvt, struct zt_pri *pri)
{
   int res;
   /* Grab the lock first */
   do {
      res = ast_mutex_trylock(&pri->lock);
      if (res) {
         ast_mutex_unlock(&pvt->lock);
         /* Release the lock and try again */
         usleep(1);
         ast_mutex_lock(&pvt->lock);
      }
   } while (res);
   /* Then break the poll */
   pthread_kill(pri->master, SIGURG);
   return 0;
}
#endif

#ifdef HAVE_SS7
static inline void ss7_rel(struct zt_ss7 *ss7)
{
   ast_mutex_unlock(&ss7->lock);
}

static inline int ss7_grab(struct zt_pvt *pvt, struct zt_ss7 *pri)
{
   int res;
   /* Grab the lock first */
   do {
      res = ast_mutex_trylock(&pri->lock);
      if (res) {
         ast_mutex_unlock(&pvt->lock);
         /* Release the lock and try again */
         usleep(1);
         ast_mutex_lock(&pvt->lock);
      }
   } while (res);
   /* Then break the poll */
   pthread_kill(pri->master, SIGURG);
   return 0;
}
#endif
#define NUM_CADENCE_MAX 25
static int num_cadence = 4;
static int user_has_defined_cadences = 0;

static struct zt_ring_cadence cadences[NUM_CADENCE_MAX] = {
   { { 125, 125, 2000, 4000 } },       /*!< Quick chirp followed by normal ring */
   { { 250, 250, 500, 1000, 250, 250, 500, 4000 } }, /*!< British style ring */
   { { 125, 125, 125, 125, 125, 4000 } }, /*!< Three short bursts */
   { { 1000, 500, 2500, 5000 } },   /*!< Long ring */
};

/*! \brief cidrings says in which pause to transmit the cid information, where the first pause
 * is 1, the second pause is 2 and so on.
 */

static int cidrings[NUM_CADENCE_MAX] = {
   2,                            /*!< Right after first long ring */
   4,                            /*!< Right after long part */
   3,                            /*!< After third chirp */
   2,                            /*!< Second spell */
};

#define ISTRUNK(p) ((p->sig == SIG_FXSLS) || (p->sig == SIG_FXSKS) || \
         (p->sig == SIG_FXSGS) || (p->sig == SIG_PRI))

#define CANBUSYDETECT(p) (ISTRUNK(p) || (p->sig & (SIG_EM | SIG_EM_E1 | SIG_SF)) /* || (p->sig & __ZT_SIG_FXO) */)
#define CANPROGRESSDETECT(p) (ISTRUNK(p) || (p->sig & (SIG_EM | SIG_EM_E1 | SIG_SF)) /* || (p->sig & __ZT_SIG_FXO) */)

static int zt_get_index(struct ast_channel *ast, struct zt_pvt *p, int nullok)
{
   int res;
   if (p->subs[0].owner == ast)
      res = 0;
   else if (p->subs[1].owner == ast)
      res = 1;
   else if (p->subs[2].owner == ast)
      res = 2;
   else {
      res = -1;
      if (!nullok)
         ast_log(LOG_WARNING, "Unable to get index, and nullok is not asserted\n");
   }
   return res;
}

#ifdef HAVE_PRI
static void wakeup_sub(struct zt_pvt *p, int a, struct zt_pri *pri)
#else
static void wakeup_sub(struct zt_pvt *p, int a, void *pri)
#endif
{
#ifdef HAVE_PRI
   if (pri)
      ast_mutex_unlock(&pri->lock);
#endif         
   for (;;) {
      if (p->subs[a].owner) {
         if (ast_mutex_trylock(&p->subs[a].owner->lock)) {
            ast_mutex_unlock(&p->lock);
            usleep(1);
            ast_mutex_lock(&p->lock);
         } else {
            ast_queue_frame(p->subs[a].owner, &ast_null_frame);
            ast_mutex_unlock(&p->subs[a].owner->lock);
            break;
         }
      } else
         break;
   }
#ifdef HAVE_PRI
   if (pri)
      ast_mutex_lock(&pri->lock);
#endif         
}

static void zap_queue_frame(struct zt_pvt *p, struct ast_frame *f, void *data)
{
#ifdef HAVE_PRI
   struct zt_pri *pri = (struct zt_pri*) data;
#endif
#ifdef HAVE_SS7
   struct zt_ss7 *ss7 = (struct zt_ss7*) data;
#endif
   /* We must unlock the PRI to avoid the possibility of a deadlock */
#if defined(HAVE_PRI) || defined(HAVE_SS7)
   if (data) {
      switch (p->sig) {
#ifdef HAVE_PRI
      case SIG_PRI:
         ast_mutex_unlock(&pri->lock);
         break;
#endif
#ifdef HAVE_SS7
      case SIG_SS7:
         ast_mutex_unlock(&ss7->lock);
         break;
#endif
      default:
         break;
      }
   }
#endif      
   for (;;) {
      if (p->owner) {
         if (ast_mutex_trylock(&p->owner->lock)) {
            ast_mutex_unlock(&p->lock);
            usleep(1);
            ast_mutex_lock(&p->lock);
         } else {
            ast_queue_frame(p->owner, f);
            ast_mutex_unlock(&p->owner->lock);
            break;
         }
      } else
         break;
   }
#if defined(HAVE_PRI) || defined(HAVE_SS7)
   if (data) {
      switch (p->sig) {
#ifdef HAVE_PRI
      case SIG_PRI:
         ast_mutex_lock(&pri->lock);
         break;
#endif
#ifdef HAVE_SS7
      case SIG_SS7:
         ast_mutex_lock(&ss7->lock);
         break;
#endif
      default:
         break;
      }
   }

#endif      
}

static int restore_gains(struct zt_pvt *p);

static void swap_subs(struct zt_pvt *p, int a, int b)
{
   int tchan;
   int tinthreeway;
   struct ast_channel *towner;

   if (option_debug)
      ast_log(LOG_DEBUG, "Swapping %d and %d\n", a, b);

   tchan = p->subs[a].chan;
   towner = p->subs[a].owner;
   tinthreeway = p->subs[a].inthreeway;

   p->subs[a].chan = p->subs[b].chan;
   p->subs[a].owner = p->subs[b].owner;
   p->subs[a].inthreeway = p->subs[b].inthreeway;

   p->subs[b].chan = tchan;
   p->subs[b].owner = towner;
   p->subs[b].inthreeway = tinthreeway;

   if (p->subs[a].owner) 
      p->subs[a].owner->fds[0] = p->subs[a].zfd;
   if (p->subs[b].owner) 
      p->subs[b].owner->fds[0] = p->subs[b].zfd;
   wakeup_sub(p, a, NULL);
   wakeup_sub(p, b, NULL);
}

static int zt_open(char *fn)
{
   int fd;
   int isnum;
   int chan = 0;
   int bs;
   int x;
   isnum = 1;
   for (x = 0; x < strlen(fn); x++) {
      if (!isdigit(fn[x])) {
         isnum = 0;
         break;
      }
   }
   if (isnum) {
      chan = atoi(fn);
      if (chan < 1) {
         ast_log(LOG_WARNING, "Invalid channel number '%s'\n", fn);
         return -1;
      }
      fn = "/dev/zap/channel";
   }
   fd = open(fn, O_RDWR | O_NONBLOCK);
   if (fd < 0) {
      ast_log(LOG_WARNING, "Unable to open '%s': %s\n", fn, strerror(errno));
      return -1;
   }
   if (chan) {
      if (ioctl(fd, ZT_SPECIFY, &chan)) {
         x = errno;
         close(fd);
         errno = x;
         ast_log(LOG_WARNING, "Unable to specify channel %d: %s\n", chan, strerror(errno));
         return -1;
      }
   }
   bs = READ_SIZE;
   if (ioctl(fd, ZT_SET_BLOCKSIZE, &bs) == -1) return -1;
   return fd;
}

static void zt_close(int fd)
{
   if (fd > 0)
      close(fd);
}

static int zt_setlinear(int zfd, int linear)
{
   int res;
   res = ioctl(zfd, ZT_SETLINEAR, &linear);
   if (res)
      return res;
   return 0;
}


static int alloc_sub(struct zt_pvt *p, int x)
{
   ZT_BUFFERINFO bi;
   int res;
   if (p->subs[x].zfd < 0) {
      p->subs[x].zfd = zt_open("/dev/zap/pseudo");
      if (p->subs[x].zfd > -1) {
         res = ioctl(p->subs[x].zfd, ZT_GET_BUFINFO, &bi);
         if (!res) {
            bi.txbufpolicy = ZT_POLICY_IMMEDIATE;
            bi.rxbufpolicy = ZT_POLICY_IMMEDIATE;
            bi.numbufs = numbufs;
            res = ioctl(p->subs[x].zfd, ZT_SET_BUFINFO, &bi);
            if (res < 0) {
               ast_log(LOG_WARNING, "Unable to set buffer policy on channel %d\n", x);
            }
         } else 
            ast_log(LOG_WARNING, "Unable to check buffer policy on channel %d\n", x);
         if (ioctl(p->subs[x].zfd, ZT_CHANNO, &p->subs[x].chan) == 1) {
            ast_log(LOG_WARNING, "Unable to get channel number for pseudo channel on FD %d\n", p->subs[x].zfd);
            zt_close(p->subs[x].zfd);
            p->subs[x].zfd = -1;
            return -1;
         }
         if (option_debug)
            ast_log(LOG_DEBUG, "Allocated %s subchannel on FD %d channel %d\n", subnames[x], p->subs[x].zfd, p->subs[x].chan);
         return 0;
      } else
         ast_log(LOG_WARNING, "Unable to open pseudo channel: %s\n", strerror(errno));
      return -1;
   }
   ast_log(LOG_WARNING, "%s subchannel of %d already in use\n", subnames[x], p->channel);
   return -1;
}

static int unalloc_sub(struct zt_pvt *p, int x)
{
   if (!x) {
      ast_log(LOG_WARNING, "Trying to unalloc the real channel %d?!?\n", p->channel);
      return -1;
   }
   if (option_debug)
      ast_log(LOG_DEBUG, "Released sub %d of channel %d\n", x, p->channel);
   if (p->subs[x].zfd > -1) {
      zt_close(p->subs[x].zfd);
   }
   p->subs[x].zfd = -1;
   p->subs[x].linear = 0;
   p->subs[x].chan = 0;
   p->subs[x].owner = NULL;
   p->subs[x].inthreeway = 0;
   p->polarity = POLARITY_IDLE;
   memset(&p->subs[x].curconf, 0, sizeof(p->subs[x].curconf));
   return 0;
}

static int digit_to_dtmfindex(char digit)
{
   if (isdigit(digit))
      return ZT_TONE_DTMF_BASE + (digit - '0');
   else if (digit >= 'A' && digit <= 'D')
      return ZT_TONE_DTMF_A + (digit - 'A');
   else if (digit >= 'a' && digit <= 'd')
      return ZT_TONE_DTMF_A + (digit - 'a');
   else if (digit == '*')
      return ZT_TONE_DTMF_s;
   else if (digit == '#')
      return ZT_TONE_DTMF_p;
   else
      return -1;
}

static int zt_digit_begin(struct ast_channel *chan, char digit)
{
   struct zt_pvt *pvt;
   int index;
   int dtmf = -1;
   
   pvt = chan->tech_pvt;

   ast_mutex_lock(&pvt->lock);

   index = zt_get_index(chan, pvt, 0);

   if ((index != SUB_REAL) || !pvt->owner)
      goto out;

#ifdef HAVE_PRI
   if ((pvt->sig == SIG_PRI) && (chan->_state == AST_STATE_DIALING) && !pvt->proceeding) {
      if (pvt->setup_ack) {
         if (!pri_grab(pvt, pvt->pri)) {
            pri_information(pvt->pri->pri, pvt->call, digit);
            pri_rel(pvt->pri);
         } else
            ast_log(LOG_WARNING, "Unable to grab PRI on span %d\n", pvt->span);
      } else if (strlen(pvt->dialdest) < sizeof(pvt->dialdest) - 1) {
         int res;
         if (option_debug)
            ast_log(LOG_DEBUG, "Queueing digit '%c' since setup_ack not yet received\n", digit);
         res = strlen(pvt->dialdest);
         pvt->dialdest[res++] = digit;
         pvt->dialdest[res] = '\0';
      }
      goto out;
   }
#endif
   if ((dtmf = digit_to_dtmfindex(digit)) == -1)
      goto out;

   if (pvt->pulse || ioctl(pvt->subs[SUB_REAL].zfd, ZT_SENDTONE, &dtmf)) {
      int res;
      ZT_DIAL_OPERATION zo = {
         .op = ZT_DIAL_OP_APPEND,
      };

      zo.dialstr[0] = 'T';
      zo.dialstr[1] = digit;
      zo.dialstr[2] = '\0';
      if ((res = ioctl(pvt->subs[SUB_REAL].zfd, ZT_DIAL, &zo)))
         ast_log(LOG_WARNING, "Couldn't dial digit %c\n", digit);
      else
         pvt->dialing = 1;
   } else {
      if (option_debug)
         ast_log(LOG_DEBUG, "Started VLDTMF digit '%c'\n", digit);
      pvt->dialing = 1;
      pvt->begindigit = digit;
   }

out:
   ast_mutex_unlock(&pvt->lock);

   return 0;
}

static int zt_digit_end(struct ast_channel *chan, char digit, unsigned int duration)
{
   struct zt_pvt *pvt;
   int res = 0;
   int index;
   int x;
   
   pvt = chan->tech_pvt;

   ast_mutex_lock(&pvt->lock);
   
   index = zt_get_index(chan, pvt, 0);

   if ((index != SUB_REAL) || !pvt->owner || pvt->pulse)
      goto out;

#ifdef HAVE_PRI
   /* This means that the digit was already sent via PRI signalling */
   if (pvt->sig == SIG_PRI && !pvt->begindigit)
      goto out;
#endif

   if (pvt->begindigit) {
      x = -1;
      if (option_debug)
         ast_log(LOG_DEBUG, "Ending VLDTMF digit '%c'\n", digit);
      res = ioctl(pvt->subs[SUB_REAL].zfd, ZT_SENDTONE, &x);
      pvt->dialing = 0;
      pvt->begindigit = 0;
   }

out:
   ast_mutex_unlock(&pvt->lock);

   return res;
}

static char *events[] = {
   "No event",
   "On hook",
   "Ring/Answered",
   "Wink/Flash",
   "Alarm",
   "No more alarm",
   "HDLC Abort",
   "HDLC Overrun",
   "HDLC Bad FCS",
   "Dial Complete",
   "Ringer On",
   "Ringer Off",
   "Hook Transition Complete",
   "Bits Changed",
   "Pulse Start",
   "Timer Expired",
   "Timer Ping",
   "Polarity Reversal",
   "Ring Begin",
};

static struct {
   int alarm;
   char *name;
} alarms[] = {
   { ZT_ALARM_RED, "Red Alarm" },
   { ZT_ALARM_YELLOW, "Yellow Alarm" },
   { ZT_ALARM_BLUE, "Blue Alarm" },
   { ZT_ALARM_RECOVER, "Recovering" },
   { ZT_ALARM_LOOPBACK, "Loopback" },
   { ZT_ALARM_NOTOPEN, "Not Open" },
   { ZT_ALARM_NONE, "None" },
};

static char *alarm2str(int alarm)
{
   int x;
   for (x = 0; x < sizeof(alarms) / sizeof(alarms[0]); x++) {
      if (alarms[x].alarm & alarm)
         return alarms[x].name;
   }
   return alarm ? "Unknown Alarm" : "No Alarm";
}

static char *event2str(int event)
{
   static char buf[256];
   if ((event < (sizeof(events) / sizeof(events[0]))) && (event > -1))
      return events[event];
   sprintf(buf, "Event %d", event); /* safe */
   return buf;
}

#ifdef HAVE_PRI
static char *dialplan2str(int dialplan)
{
   if (dialplan == -1) {
      return("Dynamically set dialplan in ISDN");
   }
   return (pri_plan2str(dialplan));
}
#endif

static char *zap_sig2str(int sig)
{
   static char buf[256];
   switch (sig) {
   case SIG_EM:
      return "E & M Immediate";
   case SIG_EMWINK:
      return "E & M Wink";
   case SIG_EM_E1:
      return "E & M E1";
   case SIG_FEATD:
      return "Feature Group D (DTMF)";
   case SIG_FEATDMF:
      return "Feature Group D (MF)";
   case SIG_FEATDMF_TA:
      return "Feature Groud D (MF) Tandem Access";
   case SIG_FEATB:
      return "Feature Group B (MF)";
   case SIG_E911:
      return "E911 (MF)";
   case SIG_FGC_CAMA:
      return "FGC/CAMA (Dialpulse)";
   case SIG_FGC_CAMAMF:
      return "FGC/CAMA (MF)";
   case SIG_FXSLS:
      return "FXS Loopstart";
   case SIG_FXSGS:
      return "FXS Groundstart";
   case SIG_FXSKS:
      return "FXS Kewlstart";
   case SIG_FXOLS:
      return "FXO Loopstart";
   case SIG_FXOGS:
      return "FXO Groundstart";
   case SIG_FXOKS:
      return "FXO Kewlstart";
   case SIG_PRI:
      return "PRI Signalling";
   case SIG_SS7:
      return "SS7 Signalling";
   case SIG_SF:
      return "SF (Tone) Signalling Immediate";
   case SIG_SFWINK:
      return "SF (Tone) Signalling Wink";
   case SIG_SF_FEATD:
      return "SF (Tone) Signalling with Feature Group D (DTMF)";
   case SIG_SF_FEATDMF:
      return "SF (Tone) Signalling with Feature Group D (MF)";
   case SIG_SF_FEATB:
      return "SF (Tone) Signalling with Feature Group B (MF)";
   case SIG_GR303FXOKS:
      return "GR-303 Signalling with FXOKS";
   case SIG_GR303FXSKS:
      return "GR-303 Signalling with FXSKS";
   case 0:
      return "Pseudo Signalling";
   default:
      snprintf(buf, sizeof(buf), "Unknown signalling %d", sig);
      return buf;
   }
}

#define sig2str zap_sig2str

static int conf_add(struct zt_pvt *p, struct zt_subchannel *c, int index, int slavechannel)
{
   /* If the conference already exists, and we're already in it
      don't bother doing anything */
   ZT_CONFINFO zi;
   
   memset(&zi, 0, sizeof(zi));
   zi.chan = 0;

   if (slavechannel > 0) {
      /* If we have only one slave, do a digital mon */
      zi.confmode = ZT_CONF_DIGITALMON;
      zi.confno = slavechannel;
   } else {
      if (!index) {
         /* Real-side and pseudo-side both participate in conference */
         zi.confmode = ZT_CONF_REALANDPSEUDO | ZT_CONF_TALKER | ZT_CONF_LISTENER |
            ZT_CONF_PSEUDO_TALKER | ZT_CONF_PSEUDO_LISTENER;
      } else
         zi.confmode = ZT_CONF_CONF | ZT_CONF_TALKER | ZT_CONF_LISTENER;
      zi.confno = p->confno;
   }
   if ((zi.confno == c->curconf.confno) && (zi.confmode == c->curconf.confmode))
      return 0;
   if (c->zfd < 0)
      return 0;
   if (ioctl(c->zfd, ZT_SETCONF, &zi)) {
      ast_log(LOG_WARNING, "Failed to add %d to conference %d/%d\n", c->zfd, zi.confmode, zi.confno);
      return -1;
   }
   if (slavechannel < 1) {
      p->confno = zi.confno;
   }
   memcpy(&c->curconf, &zi, sizeof(c->curconf));
   if (option_debug)
      ast_log(LOG_DEBUG, "Added %d to conference %d/%d\n", c->zfd, c->curconf.confmode, c->curconf.confno);
   return 0;
}

static int isourconf(struct zt_pvt *p, struct zt_subchannel *c)
{
   /* If they're listening to our channel, they're ours */  
   if ((p->channel == c->curconf.confno) && (c->curconf.confmode == ZT_CONF_DIGITALMON))
      return 1;
   /* If they're a talker on our (allocated) conference, they're ours */
   if ((p->confno > 0) && (p->confno == c->curconf.confno) && (c->curconf.confmode & ZT_CONF_TALKER))
      return 1;
   return 0;
}

static int conf_del(struct zt_pvt *p, struct zt_subchannel *c, int index)
{
   ZT_CONFINFO zi;
   if (/* Can't delete if there's no zfd */
      (c->zfd < 0) ||
      /* Don't delete from the conference if it's not our conference */
      !isourconf(p, c)
      /* Don't delete if we don't think it's conferenced at all (implied) */
      ) return 0;
   memset(&zi, 0, sizeof(zi));
   zi.chan = 0;
   zi.confno = 0;
   zi.confmode = 0;
   if (ioctl(c->zfd, ZT_SETCONF, &zi)) {
      ast_log(LOG_WARNING, "Failed to drop %d from conference %d/%d\n", c->zfd, c->curconf.confmode, c->curconf.confno);
      return -1;
   }
   if (option_debug)
      ast_log(LOG_DEBUG, "Removed %d from conference %d/%d\n", c->zfd, c->curconf.confmode, c->curconf.confno);
   memcpy(&c->curconf, &zi, sizeof(c->curconf));
   return 0;
}

static int isslavenative(struct zt_pvt *p, struct zt_pvt **out)
{
   int x;
   int useslavenative;
   struct zt_pvt *slave = NULL;
   /* Start out optimistic */
   useslavenative = 1;
   /* Update conference state in a stateless fashion */
   for (x = 0; x < 3; x++) {
      /* Any three-way calling makes slave native mode *definitely* out
         of the question */
      if ((p->subs[x].zfd > -1) && p->subs[x].inthreeway)
         useslavenative = 0;
   }
   /* If we don't have any 3-way calls, check to see if we have
      precisely one slave */
   if (useslavenative) {
      for (x = 0; x < MAX_SLAVES; x++) {
         if (p->slaves[x]) {
            if (slave) {
               /* Whoops already have a slave!  No 
                  slave native and stop right away */
               slave = NULL;
               useslavenative = 0;
               break;
            } else {
               /* We have one slave so far */
               slave = p->slaves[x];
            }
         }
      }
   }
   /* If no slave, slave native definitely out */
   if (!slave)
      useslavenative = 0;
   else if (slave->law != p->law) {
      useslavenative = 0;
      slave = NULL;
   }
   if (out)
      *out = slave;
   return useslavenative;
}

static int reset_conf(struct zt_pvt *p)
{
   ZT_CONFINFO zi;
   memset(&zi, 0, sizeof(zi));
   p->confno = -1;
   memset(&p->subs[SUB_REAL].curconf, 0, sizeof(p->subs[SUB_REAL].curconf));
   if (p->subs[SUB_REAL].zfd > -1) {
      if (ioctl(p->subs[SUB_REAL].zfd, ZT_SETCONF, &zi))
         ast_log(LOG_WARNING, "Failed to reset conferencing on channel %d!\n", p->channel);
   }
   return 0;
}

static int update_conf(struct zt_pvt *p)
{
   int needconf = 0;
   int x;
   int useslavenative;
   struct zt_pvt *slave = NULL;

   useslavenative = isslavenative(p, &slave);
   /* Start with the obvious, general stuff */
   for (x = 0; x < 3; x++) {
      /* Look for three way calls */
      if ((p->subs[x].zfd > -1) && p->subs[x].inthreeway) {
         conf_add(p, &p->subs[x], x, 0);
         needconf++;
      } else {
         conf_del(p, &p->subs[x], x);
      }
   }
   /* If we have a slave, add him to our conference now. or DAX
      if this is slave native */
   for (x = 0; x < MAX_SLAVES; x++) {
      if (p->slaves[x]) {
         if (useslavenative)
            conf_add(p, &p->slaves[x]->subs[SUB_REAL], SUB_REAL, GET_CHANNEL(p));
         else {
            conf_add(p, &p->slaves[x]->subs[SUB_REAL], SUB_REAL, 0);
            needconf++;
         }
      }
   }
   /* If we're supposed to be in there, do so now */
   if (p->inconference && !p->subs[SUB_REAL].inthreeway) {
      if (useslavenative)
         conf_add(p, &p->subs[SUB_REAL], SUB_REAL, GET_CHANNEL(slave));
      else {
         conf_add(p, &p->subs[SUB_REAL], SUB_REAL, 0);
         needconf++;
      }
   }
   /* If we have a master, add ourselves to his conference */
   if (p->master) {
      if (isslavenative(p->master, NULL)) {
         conf_add(p->master, &p->subs[SUB_REAL], SUB_REAL, GET_CHANNEL(p->master));
      } else {
         conf_add(p->master, &p->subs[SUB_REAL], SUB_REAL, 0);
      }
   }
   if (!needconf) {
      /* Nobody is left (or should be left) in our conference.
         Kill it. */
      p->confno = -1;
   }
   if (option_debug)
      ast_log(LOG_DEBUG, "Updated conferencing on %d, with %d conference users\n", p->channel, needconf);
   return 0;
}

static void zt_enable_ec(struct zt_pvt *p)
{
   int x;
   int res;
   if (!p)
      return;
   if (p->echocanon) {
      if (option_debug)
         ast_log(LOG_DEBUG, "Echo cancellation already on\n");
      return;
   }
   if (p->digital) {
      if (option_debug)
         ast_log(LOG_DEBUG, "Echo cancellation isn't required on digital connection\n");
      return;
   }
   if (p->echocancel) {
      if ((p->sig == SIG_PRI) || (p->sig == SIG_SS7)) {
         x = 1;
         res = ioctl(p->subs[SUB_REAL].zfd, ZT_AUDIOMODE, &x);
         if (res)
            ast_log(LOG_WARNING, "Unable to enable echo cancellation on channel %d\n", p->channel);
      }
      x = p->echocancel;
      res = ioctl(p->subs[SUB_REAL].zfd, ZT_ECHOCANCEL, &x);
      if (res) 
         ast_log(LOG_WARNING, "Unable to enable echo cancellation on channel %d\n", p->channel);
      else {
         p->echocanon = 1;
         if (option_debug)
            ast_log(LOG_DEBUG, "Enabled echo cancellation on channel %d\n", p->channel);
      }
   } else {
      if (option_debug)
         ast_log(LOG_DEBUG, "No echo cancellation requested\n");
   }
}

static void zt_train_ec(struct zt_pvt *p)
{
   int x;
   int res;
   if (p && p->echocancel && p->echotraining) {
      x = p->echotraining;
      res = ioctl(p->subs[SUB_REAL].zfd, ZT_ECHOTRAIN, &x);
      if (res)
         ast_log(LOG_WARNING, "Unable to request echo training on channel %d\n", p->channel);
      else {
         if (option_debug)
            ast_log(LOG_DEBUG, "Engaged echo training on channel %d\n", p->channel);
      }
   } else {
      if (option_debug)
         ast_log(LOG_DEBUG, "No echo training requested\n");
   }
}

static void zt_disable_ec(struct zt_pvt *p)
{
   int x;
   int res;
   if (p->echocancel) {
      x = 0;
      res = ioctl(p->subs[SUB_REAL].zfd, ZT_ECHOCANCEL, &x);
      if (res)
         ast_log(LOG_WARNING, "Unable to disable echo cancellation on channel %d\n", p->channel);
      else {
         if (option_debug)
            ast_log(LOG_DEBUG, "disabled echo cancellation on channel %d\n", p->channel);
      }
   }
   p->echocanon = 0;
}

static void fill_txgain(struct zt_gains *g, float gain, int law)
{
   int j;
   int k;
   float linear_gain = pow(10.0, gain / 20.0);

   switch (law) {
   case ZT_LAW_ALAW:
      for (j = 0; j < (sizeof(g->txgain) / sizeof(g->txgain[0])); j++) {
         if (gain) {
            k = (int) (((float) AST_ALAW(j)) * linear_gain);
            if (k > 32767) k = 32767;
            if (k < -32767) k = -32767;
            g->txgain[j] = AST_LIN2A(k);
         } else {
            g->txgain[j] = j;
         }
      }
      break;
   case ZT_LAW_MULAW:
      for (j = 0; j < (sizeof(g->txgain) / sizeof(g->txgain[0])); j++) {
         if (gain) {
            k = (int) (((float) AST_MULAW(j)) * linear_gain);
            if (k > 32767) k = 32767;
            if (k < -32767) k = -32767;
            g->txgain[j] = AST_LIN2MU(k);
         } else {
            g->txgain[j] = j;
         }
      }
      break;
   }
}

static void fill_rxgain(struct zt_gains *g, float gain, int law)
{
   int j;
   int k;
   float linear_gain = pow(10.0, gain / 20.0);

   switch (law) {
   case ZT_LAW_ALAW:
      for (j = 0; j < (sizeof(g->rxgain) / sizeof(g->rxgain[0])); j++) {
         if (gain) {
            k = (int) (((float) AST_ALAW(j)) * linear_gain);
            if (k > 32767) k = 32767;
            if (k < -32767) k = -32767;
            g->rxgain[j] = AST_LIN2A(k);
         } else {
            g->rxgain[j] = j;
         }
      }
      break;
   case ZT_LAW_MULAW:
      for (j = 0; j < (sizeof(g->rxgain) / sizeof(g->rxgain[0])); j++) {
         if (gain) {
            k = (int) (((float) AST_MULAW(j)) * linear_gain);
            if (k > 32767) k = 32767;
            if (k < -32767) k = -32767;
            g->rxgain[j] = AST_LIN2MU(k);
         } else {
            g->rxgain[j] = j;
         }
      }
      break;
   }
}

static int set_actual_txgain(int fd, int chan, float gain, int law)
{
   struct zt_gains g;
   int res;

   memset(&g, 0, sizeof(g));
   g.chan = chan;
   res = ioctl(fd, ZT_GETGAINS, &g);
   if (res) {
      if (option_debug)
         ast_log(LOG_DEBUG, "Failed to read gains: %s\n", strerror(errno));
      return res;
   }

   fill_txgain(&g, gain, law);

   return ioctl(fd, ZT_SETGAINS, &g);
}

static int set_actual_rxgain(int fd, int chan, float gain, int law)
{
   struct zt_gains g;
   int res;

   memset(&g, 0, sizeof(g));
   g.chan = chan;
   res = ioctl(fd, ZT_GETGAINS, &g);
   if (res) {
      if (option_debug)
         ast_log(LOG_DEBUG, "Failed to read gains: %s\n", strerror(errno));
      return res;
   }

   fill_rxgain(&g, gain, law);

   return ioctl(fd, ZT_SETGAINS, &g);
}

static int set_actual_gain(int fd, int chan, float rxgain, float txgain, int law)
{
   return set_actual_txgain(fd, chan, txgain, law) | set_actual_rxgain(fd, chan, rxgain, law);
}

static int bump_gains(struct zt_pvt *p)
{
   int res;

   /* Bump receive gain by 5.0db */
   res = set_actual_gain(p->subs[SUB_REAL].zfd, 0, p->rxgain + 5.0, p->txgain, p->law);
   if (res) {
      ast_log(LOG_WARNING, "Unable to bump gain: %s\n", strerror(errno));
      return -1;
   }

   return 0;
}

static int restore_gains(struct zt_pvt *p)
{
   int res;

   res = set_actual_gain(p->subs[SUB_REAL].zfd, 0, p->rxgain, p->txgain, p->law);
   if (res) {
      ast_log(LOG_WARNING, "Unable to restore gains: %s\n", strerror(errno));
      return -1;
   }

   return 0;
}

static inline int zt_set_hook(int fd, int hs)
{
   int x, res;
   x = hs;
   res = ioctl(fd, ZT_HOOK, &x);
   if (res < 0) 
   {
      if (errno == EINPROGRESS) return 0;
      ast_log(LOG_WARNING, "zt hook failed: %s\n", strerror(errno));
   }
   return res;
}

static inline int zt_confmute(struct zt_pvt *p, int muted)
{
   int x, y, res;
   x = muted;
   if ((p->sig == SIG_PRI) || (p->sig == SIG_SS7)) {
      y = 1;
      res = ioctl(p->subs[SUB_REAL].zfd, ZT_AUDIOMODE, &y);
      if (res)
         ast_log(LOG_WARNING, "Unable to set audio mode on '%d'\n", p->channel);
   }
   res = ioctl(p->subs[SUB_REAL].zfd, ZT_CONFMUTE, &x);
   if (res < 0)
      ast_log(LOG_WARNING, "zt confmute(%d) failed on channel %d: %s\n", muted, p->channel, strerror(errno));
   return res;
}

static int save_conference(struct zt_pvt *p)
{
   struct zt_confinfo c;
   int res;
   if (p->saveconf.confmode) {
      ast_log(LOG_WARNING, "Can't save conference -- already in use\n");
      return -1;
   }
   p->saveconf.chan = 0;
   res = ioctl(p->subs[SUB_REAL].zfd, ZT_GETCONF, &p->saveconf);
   if (res) {
      ast_log(LOG_WARNING, "Unable to get conference info: %s\n", strerror(errno));
      p->saveconf.confmode = 0;
      return -1;
   }
   c.chan = 0;
   c.confno = 0;
   c.confmode = ZT_CONF_NORMAL;
   res = ioctl(p->subs[SUB_REAL].zfd, ZT_SETCONF, &c);
   if (res) {
      ast_log(LOG_WARNING, "Unable to set conference info: %s\n", strerror(errno));
      return -1;
   }
   if (option_debug)
      ast_log(LOG_DEBUG, "Disabled conferencing\n");
   return 0;
}

static int restore_conference(struct zt_pvt *p)
{
   int res;
   if (p->saveconf.confmode) {
      res = ioctl(p->subs[SUB_REAL].zfd, ZT_SETCONF, &p->saveconf);
      p->saveconf.confmode = 0;
      if (res) {
         ast_log(LOG_WARNING, "Unable to restore conference info: %s\n", strerror(errno));
         return -1;
      }
   }
   if (option_debug)
      ast_log(LOG_DEBUG, "Restored conferencing\n");
   return 0;
}

static int send_callerid(struct zt_pvt *p);

static int send_cwcidspill(struct zt_pvt *p)
{
   p->callwaitcas = 0;
   p->cidcwexpire = 0;
   if (!(p->cidspill = ast_malloc(MAX_CALLERID_SIZE)))
      return -1;
   p->cidlen = ast_callerid_callwaiting_generate(p->cidspill, p->callwait_name, p->callwait_num, AST_LAW(p));
   /* Make sure we account for the end */
   p->cidlen += READ_SIZE * 4;
   p->cidpos = 0;
   send_callerid(p);
   if (option_verbose > 2)
      ast_verbose(VERBOSE_PREFIX_3 "CPE supports Call Waiting Caller*ID.  Sending '%s/%s'\n", p->callwait_name, p->callwait_num);
   return 0;
}

static int has_voicemail(struct zt_pvt *p)
{

   return ast_app_has_voicemail(p->mailbox, NULL);
}

static int send_callerid(struct zt_pvt *p)
{
   /* Assumes spill in p->cidspill, p->cidlen in length and we're p->cidpos into it */
   int res;
   /* Take out of linear mode if necessary */
   if (p->subs[SUB_REAL].linear) {
      p->subs[SUB_REAL].linear = 0;
      zt_setlinear(p->subs[SUB_REAL].zfd, 0);
   }
   while (p->cidpos < p->cidlen) {
      res = write(p->subs[SUB_REAL].zfd, p->cidspill + p->cidpos, p->cidlen - p->cidpos);
      if (res < 0) {
         if (errno == EAGAIN)
            return 0;
         else {
            ast_log(LOG_WARNING, "write failed: %s\n", strerror(errno));
            return -1;
         }
      }
      if (!res)
         return 0;
      p->cidpos += res;
   }
   free(p->cidspill);
   p->cidspill = NULL;
   if (p->callwaitcas) {
      /* Wait for CID/CW to expire */
      p->cidcwexpire = CIDCW_EXPIRE_SAMPLES;
   } else
      restore_conference(p);
   return 0;
}

static int zt_callwait(struct ast_channel *ast)
{
   struct zt_pvt *p = ast->tech_pvt;
   p->callwaitingrepeat = CALLWAITING_REPEAT_SAMPLES;
   if (p->cidspill) {
      ast_log(LOG_WARNING, "Spill already exists?!?\n");
      free(p->cidspill);
   }
   if (!(p->cidspill = ast_malloc(2400 /* SAS */ + 680 /* CAS */ + READ_SIZE * 4)))
      return -1;
   save_conference(p);
   /* Silence */
   memset(p->cidspill, 0x7f, 2400 + 600 + READ_SIZE * 4);
   if (!p->callwaitrings && p->callwaitingcallerid) {
      ast_gen_cas(p->cidspill, 1, 2400 + 680, AST_LAW(p));
      p->callwaitcas = 1;
      p->cidlen = 2400 + 680 + READ_SIZE * 4;
   } else {
      ast_gen_cas(p->cidspill, 1, 2400, AST_LAW(p));
      p->callwaitcas = 0;
      p->cidlen = 2400 + READ_SIZE * 4;
   }
   p->cidpos = 0;
   send_callerid(p);
   
   return 0;
}

static int zt_call(struct ast_channel *ast, char *rdest, int timeout)
{
   struct zt_pvt *p = ast->tech_pvt;
   int x, res, index,mysig;
   char *c, *n, *l;
#ifdef HAVE_PRI
   char *s = NULL;
#endif
   char dest[256]; /* must be same length as p->dialdest */
   ast_mutex_lock(&p->lock);
   ast_copy_string(dest, rdest, sizeof(dest));
   ast_copy_string(p->dialdest, rdest, sizeof(p->dialdest));
   if ((ast->_state == AST_STATE_BUSY)) {
      p->subs[SUB_REAL].needbusy = 1;
      ast_mutex_unlock(&p->lock);
      return 0;
   }
   if ((ast->_state != AST_STATE_DOWN) && (ast->_state != AST_STATE_RESERVED)) {
      ast_log(LOG_WARNING, "zt_call called on %s, neither down nor reserved\n", ast->name);
      ast_mutex_unlock(&p->lock);
      return -1;
   }
   p->dialednone = 0;
   if ((p->radio || (p->oprmode < 0)))  /* if a radio channel, up immediately */
   {
      /* Special pseudo -- automatically up */
      ast_setstate(ast, AST_STATE_UP); 
      ast_mutex_unlock(&p->lock);
      return 0;
   }
   x = ZT_FLUSH_READ | ZT_FLUSH_WRITE;
   res = ioctl(p->subs[SUB_REAL].zfd, ZT_FLUSH, &x);
   if (res)
      ast_log(LOG_WARNING, "Unable to flush input on channel %d\n", p->channel);
   p->outgoing = 1;

   set_actual_gain(p->subs[SUB_REAL].zfd, 0, p->rxgain, p->txgain, p->law);

   mysig = p->sig;
   if (p->outsigmod > -1)
      mysig = p->outsigmod;

   switch (mysig) {
   case SIG_FXOLS:
   case SIG_FXOGS:
   case SIG_FXOKS:
      if (p->owner == ast) {
         /* Normal ring, on hook */
         
         /* Don't send audio while on hook, until the call is answered */
         p->dialing = 1;
         if (p->use_callerid) {
            /* Generate the Caller-ID spill if desired */
            if (p->cidspill) {
               ast_log(LOG_WARNING, "cidspill already exists??\n");
               free(p->cidspill);
            }
            p->callwaitcas = 0;
            if ((p->cidspill = ast_malloc(MAX_CALLERID_SIZE))) {
               p->cidlen = ast_callerid_generate(p->cidspill, ast->cid.cid_name, ast->cid.cid_num, AST_LAW(p));
               p->cidpos = 0;
               send_callerid(p);
            }
         }
         /* Choose proper cadence */
         if ((p->distinctivering > 0) && (p->distinctivering <= num_cadence)) {
            if (ioctl(p->subs[SUB_REAL].zfd, ZT_SETCADENCE, &cadences[p->distinctivering - 1]))
               ast_log(LOG_WARNING, "Unable to set distinctive ring cadence %d on '%s'\n", p->distinctivering, ast->name);
            p->cidrings = cidrings[p->distinctivering - 1];
         } else {
            if (ioctl(p->subs[SUB_REAL].zfd, ZT_SETCADENCE, NULL))
               ast_log(LOG_WARNING, "Unable to reset default ring on '%s'\n", ast->name);
            p->cidrings = p->sendcalleridafter;
         }

         /* nick@dccinc.com 4/3/03 mods to allow for deferred dialing */
         c = strchr(dest, '/');
         if (c)
            c++;
         if (c && (strlen(c) < p->stripmsd)) {
            ast_log(LOG_WARNING, "Number '%s' is shorter than stripmsd (%d)\n", c, p->stripmsd);
            c = NULL;
         }
         if (c) {
            p->dop.op = ZT_DIAL_OP_REPLACE;
            snprintf(p->dop.dialstr, sizeof(p->dop.dialstr), "Tw%s", c);
            if (option_debug)
               ast_log(LOG_DEBUG, "FXO: setup deferred dialstring: %s\n", c);
         } else {
            p->dop.dialstr[0] = '\0';
         }
         x = ZT_RING;
         if (ioctl(p->subs[SUB_REAL].zfd, ZT_HOOK, &x) && (errno != EINPROGRESS)) {
            ast_log(LOG_WARNING, "Unable to ring phone: %s\n", strerror(errno));
            ast_mutex_unlock(&p->lock);
            return -1;
         }
         p->dialing = 1;
      } else {
         /* Call waiting call */
         p->callwaitrings = 0;
         if (ast->cid.cid_num)
            ast_copy_string(p->callwait_num, ast->cid.cid_num, sizeof(p->callwait_num));
         else
            p->callwait_num[0] = '\0';
         if (ast->cid.cid_name)
            ast_copy_string(p->callwait_name, ast->cid.cid_name, sizeof(p->callwait_name));
         else
            p->callwait_name[0] = '\0';
         /* Call waiting tone instead */
         if (zt_callwait(ast)) {
            ast_mutex_unlock(&p->lock);
            return -1;
         }
         /* Make ring-back */
         if (tone_zone_play_tone(p->subs[SUB_CALLWAIT].zfd, ZT_TONE_RINGTONE))
            ast_log(LOG_WARNING, "Unable to generate call-wait ring-back on channel %s\n", ast->name);
            
      }
      n = ast->cid.cid_name;
      l = ast->cid.cid_num;
      if (l)
         ast_copy_string(p->lastcid_num, l, sizeof(p->lastcid_num));
      else
         p->lastcid_num[0] = '\0';
      if (n)
         ast_copy_string(p->lastcid_name, n, sizeof(p->lastcid_name));
      else
         p->lastcid_name[0] = '\0';
      ast_setstate(ast, AST_STATE_RINGING);
      index = zt_get_index(ast, p, 0);
      if (index > -1) {
         p->subs[index].needringing = 1;
      }
      break;
   case SIG_FXSLS:
   case SIG_FXSGS:
   case SIG_FXSKS:
   case SIG_EMWINK:
   case SIG_EM:
   case SIG_EM_E1:
   case SIG_FEATD:
   case SIG_FEATDMF:
   case SIG_E911:
   case SIG_FGC_CAMA:
   case SIG_FGC_CAMAMF:
   case SIG_FEATB:
   case SIG_SFWINK:
   case SIG_SF:
   case SIG_SF_FEATD:
   case SIG_SF_FEATDMF:
   case SIG_FEATDMF_TA:
   case SIG_SF_FEATB:
      c = strchr(dest, '/');
      if (c)
         c++;
      else
         c = "";
      if (strlen(c) < p->stripmsd) {
         ast_log(LOG_WARNING, "Number '%s' is shorter than stripmsd (%d)\n", c, p->stripmsd);
         ast_mutex_unlock(&p->lock);
         return -1;
      }
#ifdef HAVE_PRI
      /* Start the trunk, if not GR-303 */
      if (!p->pri) {
#endif
         x = ZT_START;
         res = ioctl(p->subs[SUB_REAL].zfd, ZT_HOOK, &x);
         if (res < 0) {
            if (errno != EINPROGRESS) {
               ast_log(LOG_WARNING, "Unable to start channel: %s\n", strerror(errno));
               ast_mutex_unlock(&p->lock);
               return -1;
            }
         }
#ifdef HAVE_PRI
      }
#endif
      if (option_debug)
         ast_log(LOG_DEBUG, "Dialing '%s'\n", c);
      p->dop.op = ZT_DIAL_OP_REPLACE;

      c += p->stripmsd;

      switch (mysig) {
      case SIG_FEATD:
         l = ast->cid.cid_num;
         if (l) 
            snprintf(p->dop.dialstr, sizeof(p->dop.dialstr), "T*%s*%s*", l, c);
         else
            snprintf(p->dop.dialstr, sizeof(p->dop.dialstr), "T**%s*", c);
         break;
      case SIG_FEATDMF:
         l = ast->cid.cid_num;
         if (l) 
            snprintf(p->dop.dialstr, sizeof(p->dop.dialstr), "M*00%s#*%s#", l, c);
         else
            snprintf(p->dop.dialstr, sizeof(p->dop.dialstr), "M*02#*%s#", c);
         break;
      case SIG_FEATDMF_TA:
      {
         const char *cic, *ozz;

         /* If you have to go through a Tandem Access point you need to use this */
         ozz = pbx_builtin_getvar_helper(p->owner, "FEATDMF_OZZ");
         if (!ozz)
            ozz = defaultozz;
         cic = pbx_builtin_getvar_helper(p->owner, "FEATDMF_CIC");
         if (!cic)
            cic = defaultcic;
         if (!ozz || !cic) {
            ast_log(LOG_WARNING, "Unable to dial channel of type feature group D MF tandem access without CIC or OZZ set\n");
            ast_mutex_unlock(&p->lock);
            return -1;
         }
         snprintf(p->dop.dialstr, sizeof(p->dop.dialstr), "M*%s%s#", ozz, cic);
         snprintf(p->finaldial, sizeof(p->finaldial), "M*%s#", c);
         p->whichwink = 0;
      }
         break;
      case SIG_E911:
         ast_copy_string(p->dop.dialstr, "M*911#", sizeof(p->dop.dialstr));
         break;
      case SIG_FGC_CAMA:
         snprintf(p->dop.dialstr, sizeof(p->dop.dialstr), "P%s", c);
         break;
      case SIG_FGC_CAMAMF:
      case SIG_FEATB:
         snprintf(p->dop.dialstr, sizeof(p->dop.dialstr), "M*%s#", c);
         break;
      default:
         if (p->pulse)
            snprintf(p->dop.dialstr, sizeof(p->dop.dialstr), "P%sw", c);
         else
            snprintf(p->dop.dialstr, sizeof(p->dop.dialstr), "T%sw", c);
         break;
      }

      if (p->echotraining && (strlen(p->dop.dialstr) > 4)) {
         memset(p->echorest, 'w', sizeof(p->echorest) - 1);
         strcpy(p->echorest + (p->echotraining / 400) + 1, p->dop.dialstr + strlen(p->dop.dialstr) - 2);
         p->echorest[sizeof(p->echorest) - 1] = '\0';
         p->echobreak = 1;
         p->dop.dialstr[strlen(p->dop.dialstr)-2] = '\0';
      } else
         p->echobreak = 0;
      if (!res) {
         if (ioctl(p->subs[SUB_REAL].zfd, ZT_DIAL, &p->dop)) {
            x = ZT_ONHOOK;
            ioctl(p->subs[SUB_REAL].zfd, ZT_HOOK, &x);
            ast_log(LOG_WARNING, "Dialing failed on channel %d: %s\n", p->channel, strerror(errno));
            ast_mutex_unlock(&p->lock);
            return -1;
         }
      } else {
         if (option_debug)
            ast_log(LOG_DEBUG, "Deferring dialing...\n");
      }
      p->dialing = 1;
      if (ast_strlen_zero(c))
         p->dialednone = 1;
      ast_setstate(ast, AST_STATE_DIALING);
      break;
   case 0:
      /* Special pseudo -- automatically up*/
      ast_setstate(ast, AST_STATE_UP);
      break;      
   case SIG_PRI:
   case SIG_SS7:
      /* We'll get it in a moment -- but use dialdest to store pre-setup_ack digits */
      p->dialdest[0] = '\0';
      break;
   default:
      if (option_debug)
         ast_log(LOG_DEBUG, "not yet implemented\n");
      ast_mutex_unlock(&p->lock);
      return -1;
   }
#ifdef HAVE_SS7
   if (p->ss7) {
      c = strchr(dest, '/');
      if (c)
         c++;
      else
         c = dest;

      if (!p->hidecallerid) {
         l = ast->cid.cid_num;
      } else {
         l = NULL;
      }

      ss7_grab(p, p->ss7);
      p->digital = IS_DIGITAL(ast->transfercapability);
      p->ss7call = isup_new_call(p->ss7->ss7);

      if (!p->ss7call) {
         ss7_rel(p->ss7);
         ast_mutex_unlock(&p->lock);
         ast_log(LOG_ERROR, "Unable to allocate new SS7 call!\n");
         return -1;
      }

      isup_init_call(p->ss7->ss7, p->ss7call, p->cic, c + p->stripmsd, l);

      isup_iam(p->ss7->ss7, p->ss7call);
      ss7_rel(p->ss7);
   }
#endif /* HAVE_SS7 */
#ifdef HAVE_PRI
   if (p->pri) {
      struct pri_sr *sr;
#ifdef SUPPORT_USERUSER
      const char *useruser;
#endif
      int pridialplan;
      int dp_strip;
      int prilocaldialplan;
      int ldp_strip;
      int exclusive;
      const char *rr_str;
      int redirect_reason;

      c = strchr(dest, '/');
      if (c)
         c++;
      else
         c = dest;
      if (!p->hidecalleridname)
         n = ast->cid.cid_name;
      else
         n = NULL;
      if (!p->hidecallerid) {
         l = ast->cid.cid_num;
         n = ast->cid.cid_name;
      } else {
         l = NULL;
         n = NULL;
      }
      if (strlen(c) < p->stripmsd) {
         ast_log(LOG_WARNING, "Number '%s' is shorter than stripmsd (%d)\n", c, p->stripmsd);
         ast_mutex_unlock(&p->lock);
         return -1;
      }
      if (mysig != SIG_FXSKS) {
         p->dop.op = ZT_DIAL_OP_REPLACE;
         s = strchr(c + p->stripmsd, 'w');
         if (s) {
            if (strlen(s) > 1)
               snprintf(p->dop.dialstr, sizeof(p->dop.dialstr), "T%s", s);
            else
               p->dop.dialstr[0] = '\0';
            *s = '\0';
         } else {
            p->dop.dialstr[0] = '\0';
         }
      }
      if (pri_grab(p, p->pri)) {
         ast_log(LOG_WARNING, "Failed to grab PRI!\n");
         ast_mutex_unlock(&p->lock);
         return -1;
      }
      if (!(p->call = pri_new_call(p->pri->pri))) {
         ast_log(LOG_WARNING, "Unable to create call on channel %d\n", p->channel);
         pri_rel(p->pri);
         ast_mutex_unlock(&p->lock);
         return -1;
      }
      if (!(sr = pri_sr_new())) {
         ast_log(LOG_WARNING, "Failed to allocate setup request channel %d\n", p->channel);
         pri_rel(p->pri);
         ast_mutex_unlock(&p->lock);
      }
      if (p->bearer || (mysig == SIG_FXSKS)) {
         if (p->bearer) {
            if (option_debug)
               ast_log(LOG_DEBUG, "Oooh, I have a bearer on %d (%d:%d)\n", PVT_TO_CHANNEL(p->bearer), p->bearer->logicalspan, p->bearer->channel);
            p->bearer->call = p->call;
         } else {
            if (option_debug)
               ast_log(LOG_DEBUG, "I'm being setup with no bearer right now...\n");
         }
         pri_set_crv(p->pri->pri, p->call, p->channel, 0);
      }
      p->digital = IS_DIGITAL(ast->transfercapability);
      /* Add support for exclusive override */
      if (p->priexclusive)
         exclusive = 1;
      else {
      /* otherwise, traditional behavior */
         if (p->pri->nodetype == PRI_NETWORK)
            exclusive = 0;
         else
            exclusive = 1;
      }
      
      pri_sr_set_channel(sr, p->bearer ? PVT_TO_CHANNEL(p->bearer) : PVT_TO_CHANNEL(p), exclusive, 1);
      pri_sr_set_bearer(sr, p->digital ? PRI_TRANS_CAP_DIGITAL : ast->transfercapability, 
               (p->digital ? -1 : 
                  ((p->law == ZT_LAW_ALAW) ? PRI_LAYER_1_ALAW : PRI_LAYER_1_ULAW)));
      if (p->pri->facilityenable)
         pri_facility_enable(p->pri->pri);

      if (option_verbose > 2)
         ast_verbose(VERBOSE_PREFIX_3 "Requested transfer capability: 0x%.2x - %s\n", ast->transfercapability, ast_transfercapability2str(ast->transfercapability));
      dp_strip = 0;
      pridialplan = p->pri->dialplan - 1;
      if (pridialplan == -2) { /* compute dynamically */
         if (strncmp(c + p->stripmsd, p->pri->internationalprefix, strlen(p->pri->internationalprefix)) == 0) {
            dp_strip = strlen(p->pri->internationalprefix);
            pridialplan = PRI_INTERNATIONAL_ISDN;
         } else if (strncmp(c + p->stripmsd, p->pri->nationalprefix, strlen(p->pri->nationalprefix)) == 0) {
            dp_strip = strlen(p->pri->nationalprefix);
            pridialplan = PRI_NATIONAL_ISDN;
         } else {
            pridialplan = PRI_LOCAL_ISDN;
         }
      }
      pri_sr_set_called(sr, c + p->stripmsd + dp_strip, pridialplan, s ? 1 : 0);

      ldp_strip = 0;
      prilocaldialplan = p->pri->localdialplan - 1;
      if ((l != NULL) && (prilocaldialplan == -2)) { /* compute dynamically */
         if (strncmp(l, p->pri->internationalprefix, strlen(p->pri->internationalprefix)) == 0) {
            ldp_strip = strlen(p->pri->internationalprefix);
            prilocaldialplan = PRI_INTERNATIONAL_ISDN;
         } else if (strncmp(l, p->pri->nationalprefix, strlen(p->pri->nationalprefix)) == 0) {
            ldp_strip = strlen(p->pri->nationalprefix);
            prilocaldialplan = PRI_NATIONAL_ISDN;
         } else {
            prilocaldialplan = PRI_LOCAL_ISDN;
         }
      }
      pri_sr_set_caller(sr, l ? (l + ldp_strip) : NULL, n, prilocaldialplan,
         p->use_callingpres ? ast->cid.cid_pres : (l ? PRES_ALLOWED_USER_NUMBER_PASSED_SCREEN : PRES_NUMBER_NOT_AVAILABLE));
      if ((rr_str = pbx_builtin_getvar_helper(ast, "PRIREDIRECTREASON"))) {
         if (!strcasecmp(rr_str, "UNKNOWN"))
            redirect_reason = 0;
         else if (!strcasecmp(rr_str, "BUSY"))
            redirect_reason = 1;
         else if (!strcasecmp(rr_str, "NO_REPLY"))
            redirect_reason = 2;
         else if (!strcasecmp(rr_str, "UNCONDITIONAL"))
            redirect_reason = 15;
         else
            redirect_reason = PRI_REDIR_UNCONDITIONAL;
      } else
         redirect_reason = PRI_REDIR_UNCONDITIONAL;
      pri_sr_set_redirecting(sr, ast->cid.cid_rdnis, p->pri->localdialplan - 1, PRES_ALLOWED_USER_NUMBER_PASSED_SCREEN, redirect_reason);

#ifdef SUPPORT_USERUSER
      /* User-user info */
      useruser = pbx_builtin_getvar_helper(p->owner, "USERUSERINFO");

      if (useruser)
         pri_sr_set_useruser(sr, useruser);
#endif

      if (pri_setup(p->pri->pri, p->call, sr)) {
         ast_log(LOG_WARNING, "Unable to setup call to %s (using %s)\n", 
            c + p->stripmsd + dp_strip, dialplan2str(p->pri->dialplan));
         pri_rel(p->pri);
         ast_mutex_unlock(&p->lock);
         pri_sr_free(sr);
         return -1;
      }
      pri_sr_free(sr);
      ast_setstate(ast, AST_STATE_DIALING);
      pri_rel(p->pri);
   }
#endif      
   ast_mutex_unlock(&p->lock);
   return 0;
}

static void destroy_zt_pvt(struct zt_pvt **pvt)
{
   struct zt_pvt *p = *pvt;
   /* Remove channel from the list */
   if (p->prev)
      p->prev->next = p->next;
   if (p->next)
      p->next->prev = p->prev;
   if (p->use_smdi)
      ASTOBJ_UNREF(p->smdi_iface, ast_smdi_interface_destroy);
   ast_mutex_destroy(&p->lock);
   free(p);
   *pvt = NULL;
}

static int destroy_channel(struct zt_pvt *prev, struct zt_pvt *cur, int now)
{
   int owned = 0;
   int i = 0;

   if (!now) {
      if (cur->owner) {
         owned = 1;
      }

      for (i = 0; i < 3; i++) {
         if (cur->subs[i].owner) {
            owned = 1;
         }
      }
      if (!owned) {
         if (prev) {
            prev->next = cur->next;
            if (prev->next)
               prev->next->prev = prev;
            else
               ifend = prev;
         } else {
            iflist = cur->next;
            if (iflist)
               iflist->prev = NULL;
            else
               ifend = NULL;
         }
         if (cur->subs[SUB_REAL].zfd > -1) {
            zt_close(cur->subs[SUB_REAL].zfd);
         }
         destroy_zt_pvt(&cur);
      }
   } else {
      if (prev) {
         prev->next = cur->next;
         if (prev->next)
            prev->next->prev = prev;
         else
            ifend = prev;
      } else {
         iflist = cur->next;
         if (iflist)
            iflist->prev = NULL;
         else
            ifend = NULL;
      }
      if (cur->subs[SUB_REAL].zfd > -1) {
         zt_close(cur->subs[SUB_REAL].zfd);
      }
      destroy_zt_pvt(&cur);
   }
   return 0;
}

#ifdef HAVE_PRI
static char *zap_send_keypad_facility_app = "ZapSendKeypadFacility";

static char *zap_send_keypad_facility_synopsis = "Send digits out of band over a PRI";

static char *zap_send_keypad_facility_descrip = 
"  ZapSendKeypadFacility(): This application will send the given string of digits in a Keypad Facility\n"
"  IE over the current channel.\n";

static int zap_send_keypad_facility_exec(struct ast_channel *chan, void *data)
{
   /* Data will be our digit string */
   struct zt_pvt *p;
   char *digits = (char *) data;

   if (ast_strlen_zero(digits)) {
      if (option_debug)
         ast_log(LOG_DEBUG, "No digit string sent to application!\n");
      return -1;
   }

   p = (struct zt_pvt *)chan->tech_pvt;

   if (!p) {
      if (option_debug)
         ast_log(LOG_DEBUG, "Unable to find technology private\n");
      return -1;
   }

   ast_mutex_lock(&p->lock);

   if (!p->pri || !p->call) {
      if (option_debug)
         ast_log(LOG_DEBUG, "Unable to find pri or call on channel!\n");
      ast_mutex_unlock(&p->lock);
      return -1;
   }

   if (!pri_grab(p, p->pri)) {
      pri_keypad_facility(p->pri->pri, p->call, digits);
      pri_rel(p->pri);
   } else {
      if (option_debug)
         ast_log(LOG_DEBUG, "Unable to grab pri to send keypad facility!\n");
      ast_mutex_unlock(&p->lock);
      return -1;
   }

   ast_mutex_unlock(&p->lock);

   return 0;
}

static int pri_is_up(struct zt_pri *pri)
{
   int x;
   for (x = 0; x < NUM_DCHANS; x++) {
      if (pri->dchanavail[x] == DCHAN_AVAILABLE)
         return 1;
   }
   return 0;
}

static int pri_assign_bearer(struct zt_pvt *crv, struct zt_pri *pri, struct zt_pvt *bearer)
{
   bearer->owner = &inuse;
   bearer->realcall = crv;
   crv->subs[SUB_REAL].zfd = bearer->subs[SUB_REAL].zfd;
   if (crv->subs[SUB_REAL].owner)
      crv->subs[SUB_REAL].owner->fds[0] = crv->subs[SUB_REAL].zfd;
   crv->bearer = bearer;
   crv->call = bearer->call;
   crv->pri = pri;
   return 0;
}

static char *pri_order(int level)
{
   switch (level) {
   case 0:
      return "Primary";
   case 1:
      return "Secondary";
   case 2:
      return "Tertiary";
   case 3:
      return "Quaternary";
   default:
      return "<Unknown>";
   }     
}

/* Returns fd of the active dchan */
static int pri_active_dchan_fd(struct zt_pri *pri)
{
   int x = -1;

   for (x = 0; x < NUM_DCHANS; x++) {
      if ((pri->dchans[x] == pri->pri))
         break;
   }

   return pri->fds[x];
}

static int pri_find_dchan(struct zt_pri *pri)
{
   int oldslot = -1;
   struct pri *old;
   int newslot = -1;
   int x;
   old = pri->pri;
   for (x = 0; x < NUM_DCHANS; x++) {
      if ((pri->dchanavail[x] == DCHAN_AVAILABLE) && (newslot < 0))
         newslot = x;
      if (pri->dchans[x] == old) {
         oldslot = x;
      }
   }
   if (newslot < 0) {
      newslot = 0;
      ast_log(LOG_WARNING, "No D-channels available!  Using Primary channel %d as D-channel anyway!\n",
         pri->dchannels[newslot]);
   }
   if (old && (oldslot != newslot))
      ast_log(LOG_NOTICE, "Switching from from d-channel %d to channel %d!\n",
         pri->dchannels[oldslot], pri->dchannels[newslot]);
   pri->pri = pri->dchans[newslot];
   return 0;
}
#endif

static int zt_hangup(struct ast_channel *ast)
{
   int res;
   int index,x, law;
   /*static int restore_gains(struct zt_pvt *p);*/
   struct zt_pvt *p = ast->tech_pvt;
   struct zt_pvt *tmp = NULL;
   struct zt_pvt *prev = NULL;
   ZT_PARAMS par;

   if (option_debug)
      ast_log(LOG_DEBUG, "zt_hangup(%s)\n", ast->name);
   if (!ast->tech_pvt) {
      ast_log(LOG_WARNING, "Asked to hangup channel not connected\n");
      return 0;
   }
   
   ast_mutex_lock(&p->lock);
   
   index = zt_get_index(ast, p, 1);

   if ((p->sig == SIG_PRI) || (p->sig == SIG_SS7)) {
      x = 1;
      ast_channel_setoption(ast,AST_OPTION_AUDIO_MODE,&x,sizeof(char),0);
   }

   x = 0;
   zt_confmute(p, 0);
   restore_gains(p);
   if (p->origcid_num) {
      ast_copy_string(p->cid_num, p->origcid_num, sizeof(p->cid_num));
      free(p->origcid_num);
      p->origcid_num = NULL;
   }  
   if (p->origcid_name) {
      ast_copy_string(p->cid_name, p->origcid_name, sizeof(p->cid_name));
      free(p->origcid_name);
      p->origcid_name = NULL;
   }  
   if (p->dsp)
      ast_dsp_digitmode(p->dsp,DSP_DIGITMODE_DTMF | p->dtmfrelax);
   if (p->exten)
      p->exten[0] = '\0';

   if (option_debug)
      ast_log(LOG_DEBUG, "Hangup: channel: %d index = %d, normal = %d, callwait = %d, thirdcall = %d\n",
         p->channel, index, p->subs[SUB_REAL].zfd, p->subs[SUB_CALLWAIT].zfd, p->subs[SUB_THREEWAY].zfd);
   p->ignoredtmf = 0;
   
   if (index > -1) {
      /* Real channel, do some fixup */
      p->subs[index].owner = NULL;
      p->subs[index].needanswer = 0;
      p->subs[index].needflash = 0;
      p->subs[index].needringing = 0;
      p->subs[index].needbusy = 0;
      p->subs[index].needcongestion = 0;
      p->subs[index].linear = 0;
      p->subs[index].needcallerid = 0;
      p->polarity = POLARITY_IDLE;
      zt_setlinear(p->subs[index].zfd, 0);
      if (index == SUB_REAL) {
         if ((p->subs[SUB_CALLWAIT].zfd > -1) && (p->subs[SUB_THREEWAY].zfd > -1)) {
            if (option_debug)
               ast_log(LOG_DEBUG, "Normal call hung up with both three way call and a call waiting call in place?\n");
            if (p->subs[SUB_CALLWAIT].inthreeway) {
               /* We had flipped over to answer a callwait and now it's gone */
               if (option_debug)
                  ast_log(LOG_DEBUG, "We were flipped over to the callwait, moving back and unowning.\n");
               /* Move to the call-wait, but un-own us until they flip back. */
               swap_subs(p, SUB_CALLWAIT, SUB_REAL);
               unalloc_sub(p, SUB_CALLWAIT);
               p->owner = NULL;
            } else {
               /* The three way hung up, but we still have a call wait */
               if (option_debug)
                  ast_log(LOG_DEBUG, "We were in the threeway and have a callwait still.  Ditching the threeway.\n");
               swap_subs(p, SUB_THREEWAY, SUB_REAL);
               unalloc_sub(p, SUB_THREEWAY);
               if (p->subs[SUB_REAL].inthreeway) {
                  /* This was part of a three way call.  Immediately make way for
                     another call */
                  if (option_debug)
                     ast_log(LOG_DEBUG, "Call was complete, setting owner to former third call\n");
                  p->owner = p->subs[SUB_REAL].owner;
               } else {
                  /* This call hasn't been completed yet...  Set owner to NULL */
                  if (option_debug)
                     ast_log(LOG_DEBUG, "Call was incomplete, setting owner to NULL\n");
                  p->owner = NULL;
               }
               p->subs[SUB_REAL].inthreeway = 0;
            }
         } else if (p->subs[SUB_CALLWAIT].zfd > -1) {
            /* Move to the call-wait and switch back to them. */
            swap_subs(p, SUB_CALLWAIT, SUB_REAL);
            unalloc_sub(p, SUB_CALLWAIT);
            p->owner = p->subs[SUB_REAL].owner;
            if (p->owner->_state != AST_STATE_UP)
               p->subs[SUB_REAL].needanswer = 1;
            if (ast_bridged_channel(p->subs[SUB_REAL].owner))
               ast_queue_control(p->subs[SUB_REAL].owner, AST_CONTROL_UNHOLD);
         } else if (p->subs[SUB_THREEWAY].zfd > -1) {
            swap_subs(p, SUB_THREEWAY, SUB_REAL);
            unalloc_sub(p, SUB_THREEWAY);
            if (p->subs[SUB_REAL].inthreeway) {
               /* This was part of a three way call.  Immediately make way for
                  another call */
               if (option_debug)
                  ast_log(LOG_DEBUG, "Call was complete, setting owner to former third call\n");
               p->owner = p->subs[SUB_REAL].owner;
            } else {
               /* This call hasn't been completed yet...  Set owner to NULL */
               if (option_debug)
                  ast_log(LOG_DEBUG, "Call was incomplete, setting owner to NULL\n");
               p->owner = NULL;
            }
            p->subs[SUB_REAL].inthreeway = 0;
         }
      } else if (index == SUB_CALLWAIT) {
         /* Ditch the holding callwait call, and immediately make it availabe */
         if (p->subs[SUB_CALLWAIT].inthreeway) {
            /* This is actually part of a three way, placed on hold.  Place the third part
               on music on hold now */
            if (p->subs[SUB_THREEWAY].owner && ast_bridged_channel(p->subs[SUB_THREEWAY].owner)) {
               ast_queue_control_data(p->subs[SUB_THREEWAY].owner, AST_CONTROL_HOLD, 
                  S_OR(p->mohsuggest, NULL),
                  !ast_strlen_zero(p->mohsuggest) ? strlen(p->mohsuggest) + 1 : 0);
            }
            p->subs[SUB_THREEWAY].inthreeway = 0;
            /* Make it the call wait now */
            swap_subs(p, SUB_CALLWAIT, SUB_THREEWAY);
            unalloc_sub(p, SUB_THREEWAY);
         } else
            unalloc_sub(p, SUB_CALLWAIT);
      } else if (index == SUB_THREEWAY) {
         if (p->subs[SUB_CALLWAIT].inthreeway) {
            /* The other party of the three way call is currently in a call-wait state.
               Start music on hold for them, and take the main guy out of the third call */
            if (p->subs[SUB_CALLWAIT].owner && ast_bridged_channel(p->subs[SUB_CALLWAIT].owner)) {
               ast_queue_control_data(p->subs[SUB_CALLWAIT].owner, AST_CONTROL_HOLD, 
                  S_OR(p->mohsuggest, NULL),
                  !ast_strlen_zero(p->mohsuggest) ? strlen(p->mohsuggest) + 1 : 0);
            }
            p->subs[SUB_CALLWAIT].inthreeway = 0;
         }
         p->subs[SUB_REAL].inthreeway = 0;
         /* If this was part of a three way call index, let us make
            another three way call */
         unalloc_sub(p, SUB_THREEWAY);
      } else {
         /* This wasn't any sort of call, but how are we an index? */
         ast_log(LOG_WARNING, "Index found but not any type of call?\n");
      }
   }

   if (!p->subs[SUB_REAL].owner && !p->subs[SUB_CALLWAIT].owner && !p->subs[SUB_THREEWAY].owner) {
      p->owner = NULL;
      p->ringt = 0;
      p->distinctivering = 0;
      p->confirmanswer = 0;
      p->cidrings = 1;
      p->outgoing = 0;
      p->digital = 0;
      p->faxhandled = 0;
      p->pulsedial = 0;
      p->onhooktime = time(NULL);
#ifdef HAVE_PRI
      p->proceeding = 0;
      p->progress = 0;
      p->alerting = 0;
      p->setup_ack = 0;
#endif      
      if (p->dsp) {
         ast_dsp_free(p->dsp);
         p->dsp = NULL;
      }

      law = ZT_LAW_DEFAULT;
      res = ioctl(p->subs[SUB_REAL].zfd, ZT_SETLAW, &law);
      if (res < 0) 
         ast_log(LOG_WARNING, "Unable to set law on channel %d to default\n", p->channel);
      /* Perform low level hangup if no owner left */
#ifdef HAVE_SS7
      if (p->ss7) {
         if (p->ss7call) {
            if (!ss7_grab(p, p->ss7)) {
               if (!p->alreadyhungup) {
                  isup_rel(p->ss7->ss7, p->ss7call, ast->hangupcause ? ast->hangupcause : -1);
                  ss7_rel(p->ss7);
                  p->alreadyhungup = 1;
               } else
                  ast_log(LOG_WARNING, "Trying to hangup twice!\n");
            } else {
               ast_log(LOG_WARNING, "Unable to grab SS7 on CIC %d\n", p->cic);
               res = -1;
            }
         }
      }
#endif
#ifdef HAVE_PRI
      if (p->pri) {
#ifdef SUPPORT_USERUSER
         const char *useruser = pbx_builtin_getvar_helper(ast,"USERUSERINFO");
#endif

         /* Make sure we have a call (or REALLY have a call in the case of a PRI) */
         if (p->call && (!p->bearer || (p->bearer->call == p->call))) {
            if (!pri_grab(p, p->pri)) {
               if (p->alreadyhungup) {
                  if (option_debug)
                     ast_log(LOG_DEBUG, "Already hungup...  Calling hangup once, and clearing call\n");

#ifdef SUPPORT_USERUSER
                  pri_call_set_useruser(p->call, useruser);
#endif

                  pri_hangup(p->pri->pri, p->call, -1);
                  p->call = NULL;
                  if (p->bearer) 
                     p->bearer->call = NULL;
               } else {
                  const char *cause = pbx_builtin_getvar_helper(ast,"PRI_CAUSE");
                  int icause = ast->hangupcause ? ast->hangupcause : -1;
                  if (option_debug)
                     ast_log(LOG_DEBUG, "Not yet hungup...  Calling hangup once with icause, and clearing call\n");

#ifdef SUPPORT_USERUSER
                  pri_call_set_useruser(p->call, useruser);
#endif

                  p->alreadyhungup = 1;
                  if (p->bearer)
                     p->bearer->alreadyhungup = 1;
                  if (cause) {
                     if (atoi(cause))
                        icause = atoi(cause);
                  }
                  pri_hangup(p->pri->pri, p->call, icause);
               }
               if (res < 0) 
                  ast_log(LOG_WARNING, "pri_disconnect failed\n");
               pri_rel(p->pri);        
            } else {
               ast_log(LOG_WARNING, "Unable to grab PRI on span %d\n", p->span);
               res = -1;
            }
         } else {
            if (p->bearer)
               if (option_debug)
                  ast_log(LOG_DEBUG, "Bearer call is %p, while ours is still %p\n", p->bearer->call, p->call);
            p->call = NULL;
            res = 0;
         }
      }
#endif
      if (p->sig && ((p->sig != SIG_PRI) && (p->sig != SIG_SS7)))
         res = zt_set_hook(p->subs[SUB_REAL].zfd, ZT_ONHOOK);
      if (res < 0) {
         ast_log(LOG_WARNING, "Unable to hangup line %s\n", ast->name);
      }
      switch (p->sig) {
      case SIG_FXOGS:
      case SIG_FXOLS:
      case SIG_FXOKS:
         res = ioctl(p->subs[SUB_REAL].zfd, ZT_GET_PARAMS, &par);
         if (!res) {
#if 0
            if (option_debug)
               ast_log(LOG_DEBUG, "Hanging up channel %d, offhook = %d\n", p->channel, par.rxisoffhook);
#endif
            /* If they're off hook, try playing congestion */
            if ((par.rxisoffhook) && (!(p->radio || (p->oprmode < 0))))
               tone_zone_play_tone(p->subs[SUB_REAL].zfd, ZT_TONE_CONGESTION);
            else
               tone_zone_play_tone(p->subs[SUB_REAL].zfd, -1);
         }
         break;
      case SIG_FXSGS:
      case SIG_FXSLS:
      case SIG_FXSKS:
         /* Make sure we're not made available for at least two seconds assuming
            we were actually used for an inbound or outbound call. */
         if (ast->_state != AST_STATE_RESERVED) {
            time(&p->guardtime);
            p->guardtime += 2;
         }
         break;
      default:
         tone_zone_play_tone(p->subs[SUB_REAL].zfd, -1);
      }
      if (p->cidspill)
         free(p->cidspill);
      if (p->sig)
         zt_disable_ec(p);
      x = 0;
      ast_channel_setoption(ast,AST_OPTION_TONE_VERIFY,&x,sizeof(char),0);
      ast_channel_setoption(ast,AST_OPTION_TDD,&x,sizeof(char),0);
      p->didtdd = 0;
      p->cidspill = NULL;
      p->callwaitcas = 0;
      p->callwaiting = p->permcallwaiting;
      p->hidecallerid = p->permhidecallerid;
      p->dialing = 0;
      p->rdnis[0] = '\0';
      update_conf(p);
      reset_conf(p);
      /* Restore data mode */
      if ((p->sig == SIG_PRI) || (p->sig == SIG_SS7)) {
         x = 0;
         ast_channel_setoption(ast,AST_OPTION_AUDIO_MODE,&x,sizeof(char),0);
      }
#ifdef HAVE_PRI
      if (p->bearer) {
         if (option_debug)
            ast_log(LOG_DEBUG, "Freeing up bearer channel %d\n", p->bearer->channel);
         /* Free up the bearer channel as well, and
            don't use its file descriptor anymore */
         update_conf(p->bearer);
         reset_conf(p->bearer);
         p->bearer->owner = NULL;
         p->bearer->realcall = NULL;
         p->bearer = NULL;
         p->subs[SUB_REAL].zfd = -1;
         p->pri = NULL;
      }
#endif
      restart_monitor();
   }

   p->callwaitingrepeat = 0;
   p->cidcwexpire = 0;
   p->oprmode = 0;
   ast->tech_pvt = NULL;
   ast_mutex_unlock(&p->lock);
   ast_module_unref(ast_module_info->self);
   if (option_verbose > 2) 
      ast_verbose( VERBOSE_PREFIX_3 "Hungup '%s'\n", ast->name);

   ast_mutex_lock(&iflock);
   tmp = iflist;
   prev = NULL;
   if (p->destroy) {
      while (tmp) {
         if (tmp == p) {
            destroy_channel(prev, tmp, 0);
            break;
         } else {
            prev = tmp;
            tmp = tmp->next;
         }
      }
   }
   ast_mutex_unlock(&iflock);
   return 0;
}

static int zt_answer(struct ast_channel *ast)
{
   struct zt_pvt *p = ast->tech_pvt;
   int res = 0;
   int index;
   int oldstate = ast->_state;
   ast_setstate(ast, AST_STATE_UP);
   ast_mutex_lock(&p->lock);
   index = zt_get_index(ast, p, 0);
   if (index < 0)
      index = SUB_REAL;
   /* nothing to do if a radio channel */
   if ((p->radio || (p->oprmode < 0))) {
      ast_mutex_unlock(&p->lock);
      return 0;
   }
   switch (p->sig) {
   case SIG_FXSLS:
   case SIG_FXSGS:
   case SIG_FXSKS:
      p->ringt = 0;
      /* Fall through */
   case SIG_EM:
   case SIG_EM_E1:
   case SIG_EMWINK:
   case SIG_FEATD:
   case SIG_FEATDMF:
   case SIG_FEATDMF_TA:
   case SIG_E911:
   case SIG_FGC_CAMA:
   case SIG_FGC_CAMAMF:
   case SIG_FEATB:
   case SIG_SF:
   case SIG_SFWINK:
   case SIG_SF_FEATD:
   case SIG_SF_FEATDMF:
   case SIG_SF_FEATB:
   case SIG_FXOLS:
   case SIG_FXOGS:
   case SIG_FXOKS:
      /* Pick up the line */
      if (option_debug)
         ast_log(LOG_DEBUG, "Took %s off hook\n", ast->name);
      if (p->hanguponpolarityswitch) {
         gettimeofday(&p->polaritydelaytv, NULL);
      }
      res = zt_set_hook(p->subs[SUB_REAL].zfd, ZT_OFFHOOK);
      tone_zone_play_tone(p->subs[index].zfd, -1);
      p->dialing = 0;
      if ((index == SUB_REAL) && p->subs[SUB_THREEWAY].inthreeway) {
         if (oldstate == AST_STATE_RINGING) {
            if (option_debug)
               ast_log(LOG_DEBUG, "Finally swapping real and threeway\n");
            tone_zone_play_tone(p->subs[SUB_THREEWAY].zfd, -1);
            swap_subs(p, SUB_THREEWAY, SUB_REAL);
            p->owner = p->subs[SUB_REAL].owner;
         }
      }
      if (p->sig & __ZT_SIG_FXS) {
         zt_enable_ec(p);
         zt_train_ec(p);
      }
      break;
#ifdef HAVE_PRI
   case SIG_PRI:
      /* Send a pri acknowledge */
      if (!pri_grab(p, p->pri)) {
         p->proceeding = 1;
         res = pri_answer(p->pri->pri, p->call, 0, !p->digital);
         pri_rel(p->pri);
      } else {
         ast_log(LOG_WARNING, "Unable to grab PRI on span %d\n", p->span);
         res = -1;
      }
      break;
#endif
#ifdef HAVE_SS7
   case SIG_SS7:
      if (!ss7_grab(p, p->ss7)) {
         p->proceeding = 1;
         res = isup_anm(p->ss7->ss7, p->ss7call);
         ss7_rel(p->ss7);
      } else {
         ast_log(LOG_WARNING, "Unable to grab SS7 on span %d\n", p->span);
         res = -1;
      }
      break;
#endif
   case 0:
      ast_mutex_unlock(&p->lock);
      return 0;
   default:
      ast_log(LOG_WARNING, "Don't know how to answer signalling %d (channel %d)\n", p->sig, p->channel);
      res = -1;
   }
   ast_mutex_unlock(&p->lock);
   return res;
}

static int zt_setoption(struct ast_channel *chan, int option, void *data, int datalen)
{
   char *cp;
   signed char *scp;
   int x;
   int index;
   struct zt_pvt *p = chan->tech_pvt, *pp;
   struct oprmode *oprmode;
   

   /* all supported options require data */
   if (!data || (datalen < 1)) {
      errno = EINVAL;
      return -1;
   }

   switch (option) {
   case AST_OPTION_TXGAIN:
      scp = (signed char *) data;
      index = zt_get_index(chan, p, 0);
      if (index < 0) {
         ast_log(LOG_WARNING, "No index in TXGAIN?\n");
         return -1;
      }
      if (option_debug)
         ast_log(LOG_DEBUG, "Setting actual tx gain on %s to %f\n", chan->name, p->txgain + (float) *scp);
      return set_actual_txgain(p->subs[index].zfd, 0, p->txgain + (float) *scp, p->law);
   case AST_OPTION_RXGAIN:
      scp = (signed char *) data;
      index = zt_get_index(chan, p, 0);
      if (index < 0) {
         ast_log(LOG_WARNING, "No index in RXGAIN?\n");
         return -1;
      }
      if (option_debug)
         ast_log(LOG_DEBUG, "Setting actual rx gain on %s to %f\n", chan->name, p->rxgain + (float) *scp);
      return set_actual_rxgain(p->subs[index].zfd, 0, p->rxgain + (float) *scp, p->law);
   case AST_OPTION_TONE_VERIFY:
      if (!p->dsp)
         break;
      cp = (char *) data;
      switch (*cp) {
      case 1:
         if (option_debug)
            ast_log(LOG_DEBUG, "Set option TONE VERIFY, mode: MUTECONF(1) on %s\n",chan->name);
         ast_dsp_digitmode(p->dsp,DSP_DIGITMODE_MUTECONF | p->dtmfrelax);  /* set mute mode if desired */
         break;
      case 2:
         if (option_debug)
            ast_log(LOG_DEBUG, "Set option TONE VERIFY, mode: MUTECONF/MAX(2) on %s\n",chan->name);
         ast_dsp_digitmode(p->dsp,DSP_DIGITMODE_MUTECONF | DSP_DIGITMODE_MUTEMAX | p->dtmfrelax);  /* set mute mode if desired */
         break;
      default:
         if (option_debug)
            ast_log(LOG_DEBUG, "Set option TONE VERIFY, mode: OFF(0) on %s\n",chan->name);
         ast_dsp_digitmode(p->dsp,DSP_DIGITMODE_DTMF | p->dtmfrelax);  /* set mute mode if desired */
         break;
      }
      break;
   case AST_OPTION_TDD:
      /* turn on or off TDD */
      cp = (char *) data;
      p->mate = 0;
      if (!*cp) { /* turn it off */
         if (option_debug)
            ast_log(LOG_DEBUG, "Set option TDD MODE, value: OFF(0) on %s\n",chan->name);
         if (p->tdd)
            tdd_free(p->tdd);
         p->tdd = 0;
         break;
      }
      if (option_debug)
         ast_log(LOG_DEBUG, "Set option TDD MODE, value: %s(%d) on %s\n",
            (*cp == 2) ? "MATE" : "ON", (int) *cp, chan->name);
      zt_disable_ec(p);
      /* otherwise, turn it on */
      if (!p->didtdd) { /* if havent done it yet */
         unsigned char mybuf[41000], *buf;
         int size, res, fd, len;
         struct pollfd fds[1];

         buf = mybuf;
         memset(buf, 0x7f, sizeof(mybuf)); /* set to silence */
         ast_tdd_gen_ecdisa(buf + 16000, 16000);  /* put in tone */
         len = 40000;
         index = zt_get_index(chan, p, 0);
         if (index < 0) {
            ast_log(LOG_WARNING, "No index in TDD?\n");
            return -1;
         }
         fd = p->subs[index].zfd;
         while (len) {
            if (ast_check_hangup(chan))
               return -1;
            size = len;
            if (size > READ_SIZE)
               size = READ_SIZE;
            fds[0].fd = fd;
            fds[0].events = POLLPRI | POLLOUT;
            fds[0].revents = 0;
            res = poll(fds, 1, -1);
            if (!res) {
               if (option_debug)
                  ast_log(LOG_DEBUG, "poll (for write) ret. 0 on channel %d\n", p->channel);
               continue;
            }
            /* if got exception */
            if (fds[0].revents & POLLPRI)
               return -1;
            if (!(fds[0].revents & POLLOUT)) {
               if (option_debug)
                  ast_log(LOG_DEBUG, "write fd not ready on channel %d\n", p->channel);
               continue;
            }
            res = write(fd, buf, size);
            if (res != size) {
               if (res == -1) return -1;
               if (option_debug)
                  ast_log(LOG_DEBUG, "Write returned %d (%s) on channel %d\n", res, strerror(errno), p->channel);
               break;
            }
            len -= size;
            buf += size;
         }
         p->didtdd = 1; /* set to have done it now */    
      }
      if (*cp == 2) { /* Mate mode */
         if (p->tdd)
            tdd_free(p->tdd);
         p->tdd = 0;
         p->mate = 1;
         break;
      }     
      if (!p->tdd) { /* if we dont have one yet */
         p->tdd = tdd_new(); /* allocate one */
      }     
      break;
   case AST_OPTION_RELAXDTMF:  /* Relax DTMF decoding (or not) */
      if (!p->dsp)
         break;
      cp = (char *) data;
      if (option_debug)
         ast_log(LOG_DEBUG, "Set option RELAX DTMF, value: %s(%d) on %s\n",
            *cp ? "ON" : "OFF", (int) *cp, chan->name);
      ast_dsp_digitmode(p->dsp, ((*cp) ? DSP_DIGITMODE_RELAXDTMF : DSP_DIGITMODE_DTMF) | p->dtmfrelax);
      break;
   case AST_OPTION_AUDIO_MODE:  /* Set AUDIO mode (or not) */
      cp = (char *) data;
      if (!*cp) {    
         if (option_debug)
            ast_log(LOG_DEBUG, "Set option AUDIO MODE, value: OFF(0) on %s\n", chan->name);
         x = 0;
         zt_disable_ec(p);
      } else {    
         if (option_debug)
            ast_log(LOG_DEBUG, "Set option AUDIO MODE, value: ON(1) on %s\n", chan->name);
         x = 1;
      }
      if (ioctl(p->subs[SUB_REAL].zfd, ZT_AUDIOMODE, &x) == -1)
         ast_log(LOG_WARNING, "Unable to set audio mode on channel %d to %d\n", p->channel, x);
      break;
   case AST_OPTION_OPRMODE:  /* Operator services mode */
      oprmode = (struct oprmode *) data;
      pp = oprmode->peer->tech_pvt;
      p->oprmode = pp->oprmode = 0;
      /* setup peers */
      p->oprpeer = pp;
      pp->oprpeer = p;
      /* setup modes, if any */
      if (oprmode->mode) 
      {
         pp->oprmode = oprmode->mode;
         p->oprmode = -oprmode->mode;
      }
      if (option_debug)
         ast_log(LOG_DEBUG, "Set Operator Services mode, value: %d on %s/%s\n",
            oprmode->mode, chan->name,oprmode->peer->name);
      break;
   case AST_OPTION_ECHOCAN:
      cp = (char *) data;
      if (*cp) {
         if (option_debug)
            ast_log(LOG_DEBUG, "Enabling echo cancelation on %s\n", chan->name);
         zt_enable_ec(p);
      } else {
         if (option_debug)
            ast_log(LOG_DEBUG, "Disabling echo cancelation on %s\n", chan->name);
         zt_disable_ec(p);
      }
      break;
   }
   errno = 0;

   return 0;
}

static int zt_func_read(struct ast_channel *chan, const char *function, char *data, char *buf, size_t len)
{
   struct zt_pvt *p = chan->tech_pvt;
   
   if (!strcasecmp(data, "rxgain")) {
      ast_mutex_lock(&p->lock);
      snprintf(buf, len, "%f", p->rxgain);
      ast_mutex_unlock(&p->lock);   
   } else if (!strcasecmp(data, "txgain")) {
      ast_mutex_lock(&p->lock);
      snprintf(buf, len, "%f", p->txgain);
      ast_mutex_unlock(&p->lock);   
   } else {
      ast_copy_string(buf, "", len);
   }
   return 0;
}


static void zt_unlink(struct zt_pvt *slave, struct zt_pvt *master, int needlock)
{
   /* Unlink a specific slave or all slaves/masters from a given master */
   int x;
   int hasslaves;
   if (!master)
      return;
   if (needlock) {
      ast_mutex_lock(&master->lock);
      if (slave) {
         while (ast_mutex_trylock(&slave->lock)) {
            ast_mutex_unlock(&master->lock);
            usleep(1);
            ast_mutex_lock(&master->lock);
         }
      }
   }
   hasslaves = 0;
   for (x = 0; x < MAX_SLAVES; x++) {
      if (master->slaves[x]) {
         if (!slave || (master->slaves[x] == slave)) {
            /* Take slave out of the conference */
            if (option_debug)
               ast_log(LOG_DEBUG, "Unlinking slave %d from %d\n", master->slaves[x]->channel, master->channel);
            conf_del(master, &master->slaves[x]->subs[SUB_REAL], SUB_REAL);
            conf_del(master->slaves[x], &master->subs[SUB_REAL], SUB_REAL);
            master->slaves[x]->master = NULL;
            master->slaves[x] = NULL;
         } else
            hasslaves = 1;
      }
      if (!hasslaves)
         master->inconference = 0;
   }
   if (!slave) {
      if (master->master) {
         /* Take master out of the conference */
         conf_del(master->master, &master->subs[SUB_REAL], SUB_REAL);
         conf_del(master, &master->master->subs[SUB_REAL], SUB_REAL);
         hasslaves = 0;
         for (x = 0; x < MAX_SLAVES; x++) {
            if (master->master->slaves[x] == master)
               master->master->slaves[x] = NULL;
            else if (master->master->slaves[x])
               hasslaves = 1;
         }
         if (!hasslaves)
            master->master->inconference = 0;
      }
      master->master = NULL;
   }
   update_conf(master);
   if (needlock) {
      if (slave)
         ast_mutex_unlock(&slave->lock);
      ast_mutex_unlock(&master->lock);
   }
}

static void zt_link(struct zt_pvt *slave, struct zt_pvt *master) {
   int x;
   if (!slave || !master) {
      ast_log(LOG_WARNING, "Tried to link to/from NULL??\n");
      return;
   }
   for (x = 0; x < MAX_SLAVES; x++) {
      if (!master->slaves[x]) {
         master->slaves[x] = slave;
         break;
      }
   }
   if (x >= MAX_SLAVES) {
      ast_log(LOG_WARNING, "Replacing slave %d with new slave, %d\n", master->slaves[MAX_SLAVES - 1]->channel, slave->channel);
      master->slaves[MAX_SLAVES - 1] = slave;
   }
   if (slave->master) 
      ast_log(LOG_WARNING, "Replacing master %d with new master, %d\n", slave->master->channel, master->channel);
   slave->master = master;
   
   if (option_debug)
      ast_log(LOG_DEBUG, "Making %d slave to master %d at %d\n", slave->channel, master->channel, x);
}

static void disable_dtmf_detect(struct zt_pvt *p)
{
#ifdef ZT_TONEDETECT
   int val;
#endif

   p->ignoredtmf = 1;

#ifdef ZT_TONEDETECT
   val = 0;
   ioctl(p->subs[SUB_REAL].zfd, ZT_TONEDETECT, &val);
#endif      
   if (!p->hardwaredtmf && p->dsp) {
      p->dsp_features &= ~DSP_FEATURE_DTMF_DETECT;
      ast_dsp_set_features(p->dsp, p->dsp_features);
   }
}

static void enable_dtmf_detect(struct zt_pvt *p)
{
#ifdef ZT_TONEDETECT
   int val;
#endif

   if (p->channel == CHAN_PSEUDO)
      return;

   p->ignoredtmf = 0;

#ifdef ZT_TONEDETECT
   val = ZT_TONEDETECT_ON | ZT_TONEDETECT_MUTE;
   ioctl(p->subs[SUB_REAL].zfd, ZT_TONEDETECT, &val);
#endif      
   if (!p->hardwaredtmf && p->dsp) {
      p->dsp_features |= DSP_FEATURE_DTMF_DETECT;
      ast_dsp_set_features(p->dsp, p->dsp_features);
   }
}

static enum ast_bridge_result zt_bridge(struct ast_channel *c0, struct ast_channel *c1, int flags, struct ast_frame **fo, struct ast_channel **rc, int timeoutms)
{
   struct ast_channel *who;
   struct zt_pvt *p0, *p1, *op0, *op1;
   struct zt_pvt *master = NULL, *slave = NULL;
   struct ast_frame *f;
   int inconf = 0;
   int nothingok = 1;
   int ofd0, ofd1;
   int oi0, oi1, i0 = -1, i1 = -1, t0, t1;
   int os0 = -1, os1 = -1;
   int priority = 0;
   struct ast_channel *oc0, *oc1;
   enum ast_bridge_result res;

#ifdef PRI_2BCT
   int triedtopribridge = 0;
   q931_call *q931c0 = NULL, *q931c1 = NULL;
#endif

   /* For now, don't attempt to native bridge if either channel needs DTMF detection.
      There is code below to handle it properly until DTMF is actually seen,
      but due to currently unresolved issues it's ignored...
   */

   if (flags & (AST_BRIDGE_DTMF_CHANNEL_0 | AST_BRIDGE_DTMF_CHANNEL_1))
      return AST_BRIDGE_FAILED_NOWARN;

   ast_mutex_lock(&c0->lock);
   ast_mutex_lock(&c1->lock);

   p0 = c0->tech_pvt;
   p1 = c1->tech_pvt;
   /* cant do pseudo-channels here */
   if (!p0 || (!p0->sig) || !p1 || (!p1->sig)) {
      ast_mutex_unlock(&c0->lock);
      ast_mutex_unlock(&c1->lock);
      return AST_BRIDGE_FAILED_NOWARN;
   }

   oi0 = zt_get_index(c0, p0, 0);
   oi1 = zt_get_index(c1, p1, 0);
   if ((oi0 < 0) || (oi1 < 0)) {
      ast_mutex_unlock(&c0->lock);
      ast_mutex_unlock(&c1->lock);
      return AST_BRIDGE_FAILED;
   }

   op0 = p0 = c0->tech_pvt;
   op1 = p1 = c1->tech_pvt;
   ofd0 = c0->fds[0];
   ofd1 = c1->fds[0];
   oc0 = p0->owner;
   oc1 = p1->owner;

   if (ast_mutex_trylock(&p0->lock)) {
      /* Don't block, due to potential for deadlock */
      ast_mutex_unlock(&c0->lock);
      ast_mutex_unlock(&c1->lock);
      ast_log(LOG_NOTICE, "Avoiding deadlock...\n");
      return AST_BRIDGE_RETRY;
   }
   if (ast_mutex_trylock(&p1->lock)) {
      /* Don't block, due to potential for deadlock */
      ast_mutex_unlock(&p0->lock);
      ast_mutex_unlock(&c0->lock);
      ast_mutex_unlock(&c1->lock);
      ast_log(LOG_NOTICE, "Avoiding deadlock...\n");
      return AST_BRIDGE_RETRY;
   }

   if ((oi0 == SUB_REAL) && (oi1 == SUB_REAL)) {
      if (p0->owner && p1->owner) {
         /* If we don't have a call-wait in a 3-way, and we aren't in a 3-way, we can be master */
         if (!p0->subs[SUB_CALLWAIT].inthreeway && !p1->subs[SUB_REAL].inthreeway) {
            master = p0;
            slave = p1;
            inconf = 1;
         } else if (!p1->subs[SUB_CALLWAIT].inthreeway && !p0->subs[SUB_REAL].inthreeway) {
            master = p1;
            slave = p0;
            inconf = 1;
         } else {
            ast_log(LOG_WARNING, "Huh?  Both calls are callwaits or 3-ways?  That's clever...?\n");
            ast_log(LOG_WARNING, "p0: chan %d/%d/CW%d/3W%d, p1: chan %d/%d/CW%d/3W%d\n",
               p0->channel,
               oi0, (p0->subs[SUB_CALLWAIT].zfd > -1) ? 1 : 0,
               p0->subs[SUB_REAL].inthreeway, p0->channel,
               oi0, (p1->subs[SUB_CALLWAIT].zfd > -1) ? 1 : 0,
               p1->subs[SUB_REAL].inthreeway);
         }
         nothingok = 0;
      }
   } else if ((oi0 == SUB_REAL) && (oi1 == SUB_THREEWAY)) {
      if (p1->subs[SUB_THREEWAY].inthreeway) {
         master = p1;
         slave = p0;
         nothingok = 0;
      }
   } else if ((oi0 == SUB_THREEWAY) && (oi1 == SUB_REAL)) {
      if (p0->subs[SUB_THREEWAY].inthreeway) {
         master = p0;
         slave = p1;
         nothingok = 0;
      }
   } else if ((oi0 == SUB_REAL) && (oi1 == SUB_CALLWAIT)) {
      /* We have a real and a call wait.  If we're in a three way call, put us in it, otherwise, 
         don't put us in anything */
      if (p1->subs[SUB_CALLWAIT].inthreeway) {
         master = p1;
         slave = p0;
         nothingok = 0;
      }
   } else if ((oi0 == SUB_CALLWAIT) && (oi1 == SUB_REAL)) {
      /* Same as previous */
      if (p0->subs[SUB_CALLWAIT].inthreeway) {
         master = p0;
         slave = p1;
         nothingok = 0;
      }
   }
   if (option_debug)
      ast_log(LOG_DEBUG, "master: %d, slave: %d, nothingok: %d\n",
         master ? master->channel : 0, slave ? slave->channel : 0, nothingok);
   if (master && slave) {
      /* Stop any tones, or play ringtone as appropriate.  If they're bridged
         in an active threeway call with a channel that is ringing, we should
         indicate ringing. */
      if ((oi1 == SUB_THREEWAY) && 
          p1->subs[SUB_THREEWAY].inthreeway && 
          p1->subs[SUB_REAL].owner && 
          p1->subs[SUB_REAL].inthreeway && 
          (p1->subs[SUB_REAL].owner->_state == AST_STATE_RINGING)) {
         if (option_debug)
            ast_log(LOG_DEBUG, "Playing ringback on %s since %s is in a ringing three-way\n", c0->name, c1->name);
         tone_zone_play_tone(p0->subs[oi0].zfd, ZT_TONE_RINGTONE);
         os1 = p1->subs[SUB_REAL].owner->_state;
      } else {
         if (option_debug)
            ast_log(LOG_DEBUG, "Stopping tones on %d/%d talking to %d/%d\n", p0->channel, oi0, p1->channel, oi1);
         tone_zone_play_tone(p0->subs[oi0].zfd, -1);
      }
      if ((oi0 == SUB_THREEWAY) && 
          p0->subs[SUB_THREEWAY].inthreeway && 
          p0->subs[SUB_REAL].owner && 
          p0->subs[SUB_REAL].inthreeway && 
          (p0->subs[SUB_REAL].owner->_state == AST_STATE_RINGING)) {
         if (option_debug)
            ast_log(LOG_DEBUG, "Playing ringback on %s since %s is in a ringing three-way\n", c1->name, c0->name);
         tone_zone_play_tone(p1->subs[oi1].zfd, ZT_TONE_RINGTONE);
         os0 = p0->subs[SUB_REAL].owner->_state;
      } else {
         if (option_debug)
            ast_log(LOG_DEBUG, "Stopping tones on %d/%d talking to %d/%d\n", p1->channel, oi1, p0->channel, oi0);
         tone_zone_play_tone(p1->subs[oi0].zfd, -1);
      }
      if ((oi0 == SUB_REAL) && (oi1 == SUB_REAL)) {
         if (!p0->echocanbridged || !p1->echocanbridged) {
            /* Disable echo cancellation if appropriate */
            zt_disable_ec(p0);
            zt_disable_ec(p1);
         }
      }
      zt_link(slave, master);
      master->inconference = inconf;
   } else if (!nothingok)
      ast_log(LOG_WARNING, "Can't link %d/%s with %d/%s\n", p0->channel, subnames[oi0], p1->channel, subnames[oi1]);

   update_conf(p0);
   update_conf(p1);
   t0 = p0->subs[SUB_REAL].inthreeway;
   t1 = p1->subs[SUB_REAL].inthreeway;

   ast_mutex_unlock(&p0->lock);
   ast_mutex_unlock(&p1->lock);

   ast_mutex_unlock(&c0->lock);
   ast_mutex_unlock(&c1->lock);

   /* Native bridge failed */
   if ((!master || !slave) && !nothingok) {
      zt_enable_ec(p0);
      zt_enable_ec(p1);
      return AST_BRIDGE_FAILED;
   }
   
   if (option_verbose > 2) 
      ast_verbose(VERBOSE_PREFIX_3 "Native bridging %s and %s\n", c0->name, c1->name);

   if (!(flags & AST_BRIDGE_DTMF_CHANNEL_0) && (oi0 == SUB_REAL))
      disable_dtmf_detect(op0);

   if (!(flags & AST_BRIDGE_DTMF_CHANNEL_1) && (oi1 == SUB_REAL))
      disable_dtmf_detect(op1);

   for (;;) {
      struct ast_channel *c0_priority[2] = {c0, c1};
      struct ast_channel *c1_priority[2] = {c1, c0};

      /* Here's our main loop...  Start by locking things, looking for private parts, 
         and then balking if anything is wrong */
      ast_mutex_lock(&c0->lock);
      ast_mutex_lock(&c1->lock);
      p0 = c0->tech_pvt;
      p1 = c1->tech_pvt;

      if (op0 == p0)
         i0 = zt_get_index(c0, p0, 1);
      if (op1 == p1)
         i1 = zt_get_index(c1, p1, 1);
      ast_mutex_unlock(&c0->lock);
      ast_mutex_unlock(&c1->lock);

      if (!timeoutms || 
          (op0 != p0) ||
          (op1 != p1) || 
          (ofd0 != c0->fds[0]) || 
          (ofd1 != c1->fds[0]) ||
          (p0->subs[SUB_REAL].owner && (os0 > -1) && (os0 != p0->subs[SUB_REAL].owner->_state)) || 
          (p1->subs[SUB_REAL].owner && (os1 > -1) && (os1 != p1->subs[SUB_REAL].owner->_state)) || 
          (oc0 != p0->owner) || 
          (oc1 != p1->owner) ||
          (t0 != p0->subs[SUB_REAL].inthreeway) ||
          (t1 != p1->subs[SUB_REAL].inthreeway) ||
          (oi0 != i0) ||
          (oi1 != i1)) {
         if (option_debug)
            ast_log(LOG_DEBUG, "Something changed out on %d/%d to %d/%d, returning -3 to restart\n",
               op0->channel, oi0, op1->channel, oi1);
         res = AST_BRIDGE_RETRY;
         goto return_from_bridge;
      }

#ifdef PRI_2BCT
      q931c0 = p0->call;
      q931c1 = p1->call;
      if (p0->transfer && p1->transfer 
          && q931c0 && q931c1 
          && !triedtopribridge) {
         pri_channel_bridge(q931c0, q931c1);
         triedtopribridge = 1;
      }
#endif

      who = ast_waitfor_n(priority ? c0_priority : c1_priority, 2, &timeoutms);
      if (!who) {
         if (option_debug)
            ast_log(LOG_DEBUG, "Ooh, empty read...\n");
         continue;
      }
      f = ast_read(who);
      if (!f || (f->frametype == AST_FRAME_CONTROL)) {
         *fo = f;
         *rc = who;
         res = AST_BRIDGE_COMPLETE;
         goto return_from_bridge;
      }
      if (f->frametype ==