sig_analog.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2009, 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 Analog signaling module
 *
 * \author Matthew Fredrickson <creslin@digium.com>
 */

/*** MODULEINFO
	<support_level>core</support_level>
 ***/

#include "asterisk.h"

#include <errno.h>
#include <ctype.h>

#include "asterisk/utils.h"
#include "asterisk/options.h"
#include "asterisk/pickup.h"
#include "asterisk/pbx.h"
#include "asterisk/file.h"
#include "asterisk/callerid.h"
#include "asterisk/say.h"
#include "asterisk/manager.h"
#include "asterisk/astdb.h"
#include "asterisk/features.h"
#include "asterisk/causes.h"
#include "asterisk/features_config.h"
#include "asterisk/bridge.h"
#include "asterisk/parking.h"

#include "sig_analog.h"

/*** DOCUMENTATION
 ***/

/*! \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 DAHDI_CHECK_HOOKSTATE */

#define POLARITY_IDLE 0
#define POLARITY_REV    1
#define MIN_MS_SINCE_FLASH			( (2000) )	/*!< 2000 ms */
static int analog_matchdigittimeout = 3000;
static int analog_gendigittimeout = 8000;
static int analog_firstdigittimeout = 16000;
static char analog_defaultcic[64] = "";
static char analog_defaultozz[64] = "";

static const struct {
	enum analog_sigtype sigtype;
	const char const *name;
} sigtypes[] = {
	{ ANALOG_SIG_FXOLS, "fxo_ls" },
	{ ANALOG_SIG_FXOKS, "fxo_ks" },
	{ ANALOG_SIG_FXOGS, "fxo_gs" },
	{ ANALOG_SIG_FXSLS, "fxs_ls" },
	{ ANALOG_SIG_FXSKS, "fxs_ks" },
	{ ANALOG_SIG_FXSGS, "fxs_gs" },
	{ ANALOG_SIG_EMWINK, "em_w" },
	{ ANALOG_SIG_EM, "em" },
	{ ANALOG_SIG_EM_E1, "em_e1" },
	{ ANALOG_SIG_FEATD, "featd" },
	{ ANALOG_SIG_FEATDMF, "featdmf" },
	{ ANALOG_SIG_FEATDMF_TA, "featdmf_ta" },
	{ ANALOG_SIG_FEATB, "featb" },
	{ ANALOG_SIG_FGC_CAMA, "fgccama" },
	{ ANALOG_SIG_FGC_CAMAMF, "fgccamamf" },
	{ ANALOG_SIG_SF, "sf" },
	{ ANALOG_SIG_SFWINK, "sf_w" },
	{ ANALOG_SIG_SF_FEATD, "sf_featd" },
	{ ANALOG_SIG_SF_FEATDMF, "sf_featdmf" },
	{ ANALOG_SIG_SF_FEATB, "sf_featb" },
	{ ANALOG_SIG_E911, "e911" },
};

static const struct {
	unsigned int cid_type;
	const char const *name;
} cidtypes[] = {
	{ CID_SIG_BELL,   "bell" },
	{ CID_SIG_V23,    "v23" },
	{ CID_SIG_V23_JP, "v23_jp" },
	{ CID_SIG_DTMF,   "dtmf" },
	/* "smdi" is intentionally not supported here, as there is a much better
	 * way to do this in the dialplan now. */
};

#define ISTRUNK(p) ((p->sig == ANALOG_SIG_FXSLS) || (p->sig == ANALOG_SIG_FXSKS) || \
					(p->sig == ANALOG_SIG_FXSGS))

enum analog_sigtype analog_str_to_sigtype(const char *name)
{
	int i;

	for (i = 0; i < ARRAY_LEN(sigtypes); i++) {
		if (!strcasecmp(sigtypes[i].name, name)) {
			return sigtypes[i].sigtype;
		}
	}

	return 0;
}

const char *analog_sigtype_to_str(enum analog_sigtype sigtype)
{
	int i;

	for (i = 0; i < ARRAY_LEN(sigtypes); i++) {
		if (sigtype == sigtypes[i].sigtype) {
			return sigtypes[i].name;
		}
	}

	return "Unknown";
}

unsigned int analog_str_to_cidtype(const char *name)
{
	int i;

	for (i = 0; i < ARRAY_LEN(cidtypes); i++) {
		if (!strcasecmp(cidtypes[i].name, name)) {
			return cidtypes[i].cid_type;
		}
	}

	return 0;
}

const char *analog_cidtype_to_str(unsigned int cid_type)
{
	int i;

	for (i = 0; i < ARRAY_LEN(cidtypes); i++) {
		if (cid_type == cidtypes[i].cid_type) {
			return cidtypes[i].name;
		}
	}

	return "Unknown";
}

static int analog_start_cid_detect(struct analog_pvt *p, int cid_signalling)
{
	if (analog_callbacks.start_cid_detect) {
		return analog_callbacks.start_cid_detect(p->chan_pvt, cid_signalling);
	}
	return -1;
}

static int analog_stop_cid_detect(struct analog_pvt *p)
{
	if (analog_callbacks.stop_cid_detect) {
		return analog_callbacks.stop_cid_detect(p->chan_pvt);
	}
	return -1;
}

static int analog_get_callerid(struct analog_pvt *p, char *name, char *number, enum analog_event *ev, size_t timeout)
{
	if (analog_callbacks.get_callerid) {
		return analog_callbacks.get_callerid(p->chan_pvt, name, number, ev, timeout);
	}
	return -1;
}

static const char *analog_get_orig_dialstring(struct analog_pvt *p)
{
	if (analog_callbacks.get_orig_dialstring) {
		return analog_callbacks.get_orig_dialstring(p->chan_pvt);
	}
	return "";
}

static int analog_get_event(struct analog_pvt *p)
{
	if (analog_callbacks.get_event) {
		return analog_callbacks.get_event(p->chan_pvt);
	}
	return -1;
}

static int analog_wait_event(struct analog_pvt *p)
{
	if (analog_callbacks.wait_event) {
		return analog_callbacks.wait_event(p->chan_pvt);
	}
	return -1;
}

static int analog_have_progressdetect(struct analog_pvt *p)
{
	if (analog_callbacks.have_progressdetect) {
		return analog_callbacks.have_progressdetect(p->chan_pvt);
	}
	/* Don't have progress detection. */
	return 0;
}

enum analog_cid_start analog_str_to_cidstart(const char *value)
{
	if (!strcasecmp(value, "ring")) {
		return ANALOG_CID_START_RING;
	} else if (!strcasecmp(value, "polarity")) {
		return ANALOG_CID_START_POLARITY;
	} else if (!strcasecmp(value, "polarity_in")) {
		return ANALOG_CID_START_POLARITY_IN;
	} else if (!strcasecmp(value, "dtmf")) {
		return ANALOG_CID_START_DTMF_NOALERT;
	}

	return 0;
}

const char *analog_cidstart_to_str(enum analog_cid_start cid_start)
{
	switch (cid_start) {
	case ANALOG_CID_START_RING:
		return "Ring";
	case ANALOG_CID_START_POLARITY:
		return "Polarity";
	case ANALOG_CID_START_POLARITY_IN:
		return "Polarity_In";
	case ANALOG_CID_START_DTMF_NOALERT:
		return "DTMF";
	}

	return "Unknown";
}

static char *analog_event2str(enum analog_event event)
{
	char *res;
	switch (event) {
	case ANALOG_EVENT_ONHOOK:
		res = "ANALOG_EVENT_ONHOOK";
		break;
	case ANALOG_EVENT_RINGOFFHOOK:
		res = "ANALOG_EVENT_RINGOFFHOOK";
		break;
	case ANALOG_EVENT_WINKFLASH:
		res = "ANALOG_EVENT_WINKFLASH";
		break;
	case ANALOG_EVENT_ALARM:
		res = "ANALOG_EVENT_ALARM";
		break;
	case ANALOG_EVENT_NOALARM:
		res = "ANALOG_EVENT_NOALARM";
		break;
	case ANALOG_EVENT_DIALCOMPLETE:
		res = "ANALOG_EVENT_DIALCOMPLETE";
		break;
	case ANALOG_EVENT_HOOKCOMPLETE:
		res = "ANALOG_EVENT_HOOKCOMPLETE";
		break;
	case ANALOG_EVENT_PULSE_START:
		res = "ANALOG_EVENT_PULSE_START";
		break;
	case ANALOG_EVENT_POLARITY:
		res = "ANALOG_EVENT_POLARITY";
		break;
	case ANALOG_EVENT_RINGBEGIN:
		res = "ANALOG_EVENT_RINGBEGIN";
		break;
	case ANALOG_EVENT_EC_DISABLED:
		res = "ANALOG_EVENT_EC_DISABLED";
		break;
	case ANALOG_EVENT_RINGERON:
		res = "ANALOG_EVENT_RINGERON";
		break;
	case ANALOG_EVENT_RINGEROFF:
		res = "ANALOG_EVENT_RINGEROFF";
		break;
	case ANALOG_EVENT_REMOVED:
		res = "ANALOG_EVENT_REMOVED";
		break;
	case ANALOG_EVENT_NEONMWI_ACTIVE:
		res = "ANALOG_EVENT_NEONMWI_ACTIVE";
		break;
	case ANALOG_EVENT_NEONMWI_INACTIVE:
		res = "ANALOG_EVENT_NEONMWI_INACTIVE";
		break;
#ifdef HAVE_DAHDI_ECHOCANCEL_FAX_MODE
	case ANALOG_EVENT_TX_CED_DETECTED:
		res = "ANALOG_EVENT_TX_CED_DETECTED";
		break;
	case ANALOG_EVENT_RX_CED_DETECTED:
		res = "ANALOG_EVENT_RX_CED_DETECTED";
		break;
	case ANALOG_EVENT_EC_NLP_DISABLED:
		res = "ANALOG_EVENT_EC_NLP_DISABLED";
		break;
	case ANALOG_EVENT_EC_NLP_ENABLED:
		res = "ANALOG_EVENT_EC_NLP_ENABLED";
		break;
#endif
	case ANALOG_EVENT_PULSEDIGIT:
		res = "ANALOG_EVENT_PULSEDIGIT";
		break;
	case ANALOG_EVENT_DTMFDOWN:
		res = "ANALOG_EVENT_DTMFDOWN";
		break;
	case ANALOG_EVENT_DTMFUP:
		res = "ANALOG_EVENT_DTMFUP";
		break;
	default:
		res = "UNKNOWN/OTHER";
		break;
	}

	return res;
}

static void analog_swap_subs(struct analog_pvt *p, enum analog_sub a, enum analog_sub b)
{
	int tinthreeway;
	struct ast_channel *towner;

	ast_debug(1, "Swapping %u and %u\n", a, b);

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

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

	if (analog_callbacks.swap_subs) {
		analog_callbacks.swap_subs(p->chan_pvt, a, p->subs[a].owner, b, p->subs[b].owner);
	}
}

static int analog_alloc_sub(struct analog_pvt *p, enum analog_sub x)
{
	if (analog_callbacks.allocate_sub) {
		int res;
		res = analog_callbacks.allocate_sub(p->chan_pvt, x);
		if (!res) {
			p->subs[x].allocd = 1;
		}
		return res;
	}
	return 0;
}

static int analog_unalloc_sub(struct analog_pvt *p, enum analog_sub x)
{
	p->subs[x].allocd = 0;
	p->subs[x].owner = NULL;
	if (analog_callbacks.unallocate_sub) {
		return analog_callbacks.unallocate_sub(p->chan_pvt, x);
	}
	return 0;
}

static int analog_send_callerid(struct analog_pvt *p, int cwcid, struct ast_party_caller *caller)
{
	ast_debug(1, "Sending callerid.  CID_NAME: '%s' CID_NUM: '%s'\n",
		caller->id.name.str,
		caller->id.number.str);

	if (cwcid) {
		p->callwaitcas = 0;
	}

	if (analog_callbacks.send_callerid) {
		return analog_callbacks.send_callerid(p->chan_pvt, cwcid, caller);
	}
	return 0;
}

#define analog_get_index(ast, p, nullok)	_analog_get_index(ast, p, nullok, __PRETTY_FUNCTION__, __LINE__)
static int _analog_get_index(struct ast_channel *ast, struct analog_pvt *p, int nullok, const char *fname, unsigned long line)
{
	int res;
	if (p->subs[ANALOG_SUB_REAL].owner == ast) {
		res = ANALOG_SUB_REAL;
	} else if (p->subs[ANALOG_SUB_CALLWAIT].owner == ast) {
		res = ANALOG_SUB_CALLWAIT;
	} else if (p->subs[ANALOG_SUB_THREEWAY].owner == ast) {
		res = ANALOG_SUB_THREEWAY;
	} else {
		res = -1;
		if (!nullok) {
			ast_log(LOG_WARNING,
				"Unable to get index for '%s' on channel %d (%s(), line %lu)\n",
				ast ? ast_channel_name(ast) : "", p->channel, fname, line);
		}
	}
	return res;
}

static int analog_dsp_reset_and_flush_digits(struct analog_pvt *p)
{
	if (analog_callbacks.dsp_reset_and_flush_digits) {
		return analog_callbacks.dsp_reset_and_flush_digits(p->chan_pvt);
	}

	/* Return 0 since I think this is unnecessary to do in most cases it is used.  Mostly only for ast_dsp */
	return 0;
}

static int analog_play_tone(struct analog_pvt *p, enum analog_sub sub, enum analog_tone tone)
{
	if (analog_callbacks.play_tone) {
		return analog_callbacks.play_tone(p->chan_pvt, sub, tone);
	}
	return -1;
}

static void analog_set_new_owner(struct analog_pvt *p, struct ast_channel *new_owner)
{
	p->owner = new_owner;
	if (analog_callbacks.set_new_owner) {
		analog_callbacks.set_new_owner(p->chan_pvt, new_owner);
	}
}

static struct ast_channel * analog_new_ast_channel(struct analog_pvt *p, int state, int startpbx, enum analog_sub sub, const struct ast_channel *requestor)
{
	struct ast_channel *c;

	if (!analog_callbacks.new_ast_channel) {
		return NULL;
	}

	c = analog_callbacks.new_ast_channel(p->chan_pvt, state, startpbx, sub, requestor);
	if (c) {
		ast_channel_call_forward_set(c, p->call_forward);
	}
	p->subs[sub].owner = c;
	if (!p->owner) {
		analog_set_new_owner(p, c);
	}
	return c;
}

static int analog_set_echocanceller(struct analog_pvt *p, int enable)
{
	if (analog_callbacks.set_echocanceller) {
		return analog_callbacks.set_echocanceller(p->chan_pvt, enable);
	}
	return -1;
}

static int analog_train_echocanceller(struct analog_pvt *p)
{
	if (analog_callbacks.train_echocanceller) {
		return analog_callbacks.train_echocanceller(p->chan_pvt);
	}
	return -1;
}

static int analog_is_off_hook(struct analog_pvt *p)
{
	if (analog_callbacks.is_off_hook) {
		return analog_callbacks.is_off_hook(p->chan_pvt);
	}
	return -1;
}

static int analog_ring(struct analog_pvt *p)
{
	if (analog_callbacks.ring) {
		return analog_callbacks.ring(p->chan_pvt);
	}
	return -1;
}

static int analog_flash(struct analog_pvt *p)
{
	if (analog_callbacks.flash) {
		return analog_callbacks.flash(p->chan_pvt);
	}
	return -1;
}

static int analog_start(struct analog_pvt *p)
{
	if (analog_callbacks.start) {
		return analog_callbacks.start(p->chan_pvt);
	}
	return -1;
}

static int analog_dial_digits(struct analog_pvt *p, enum analog_sub sub, struct analog_dialoperation *dop)
{
	if (analog_callbacks.dial_digits) {
		return analog_callbacks.dial_digits(p->chan_pvt, sub, dop);
	}
	return -1;
}

static int analog_on_hook(struct analog_pvt *p)
{
	if (analog_callbacks.on_hook) {
		return analog_callbacks.on_hook(p->chan_pvt);
	}
	return -1;
}

static void analog_set_outgoing(struct analog_pvt *p, int is_outgoing)
{
	p->outgoing = is_outgoing;
	if (analog_callbacks.set_outgoing) {
		analog_callbacks.set_outgoing(p->chan_pvt, is_outgoing);
	}
}

static int analog_check_for_conference(struct analog_pvt *p)
{
	if (analog_callbacks.check_for_conference) {
		return analog_callbacks.check_for_conference(p->chan_pvt);
	}
	return -1;
}

static void analog_all_subchannels_hungup(struct analog_pvt *p)
{
	if (analog_callbacks.all_subchannels_hungup) {
		analog_callbacks.all_subchannels_hungup(p->chan_pvt);
	}
}

static void analog_unlock_private(struct analog_pvt *p)
{
	if (analog_callbacks.unlock_private) {
		analog_callbacks.unlock_private(p->chan_pvt);
	}
}

static void analog_lock_private(struct analog_pvt *p)
{
	if (analog_callbacks.lock_private) {
		analog_callbacks.lock_private(p->chan_pvt);
	}
}

static void analog_deadlock_avoidance_private(struct analog_pvt *p)
{
	if (analog_callbacks.deadlock_avoidance_private) {
		analog_callbacks.deadlock_avoidance_private(p->chan_pvt);
	} else {
		/* Fallback to manual avoidance if callback not present. */
		analog_unlock_private(p);
		usleep(1);
		analog_lock_private(p);
	}
}

/*!
 * \internal
 * \brief Obtain the specified subchannel owner lock if the owner exists.
 *
 * \param pvt Analog private struct.
 * \param sub_idx Subchannel owner to lock.
 *
 * \note Assumes the analog_lock_private(pvt->chan_pvt) is already obtained.
 *
 * \note
 * Because deadlock avoidance may have been necessary, you need to confirm
 * the state of things before continuing.
 *
 * \return Nothing
 */
static void analog_lock_sub_owner(struct analog_pvt *pvt, enum analog_sub sub_idx)
{
	for (;;) {
		if (!pvt->subs[sub_idx].owner) {
			/* No subchannel owner pointer */
			break;
		}
		if (!ast_channel_trylock(pvt->subs[sub_idx].owner)) {
			/* Got subchannel owner lock */
			break;
		}
		/* We must unlock the private to avoid the possibility of a deadlock */
		analog_deadlock_avoidance_private(pvt);
	}
}

static int analog_off_hook(struct analog_pvt *p)
{
	if (analog_callbacks.off_hook) {
		return analog_callbacks.off_hook(p->chan_pvt);
	}
	return -1;
}

static void analog_set_needringing(struct analog_pvt *p, int value)
{
	if (analog_callbacks.set_needringing) {
		analog_callbacks.set_needringing(p->chan_pvt, value);
	}
}

#if 0
static void analog_set_polarity(struct analog_pvt *p, int value)
{
	if (analog_callbacks.set_polarity) {
		analog_callbacks.set_polarity(p->chan_pvt, value);
	}
}
#endif

static void analog_start_polarityswitch(struct analog_pvt *p)
{
	if (analog_callbacks.start_polarityswitch) {
		analog_callbacks.start_polarityswitch(p->chan_pvt);
	}
}
static void analog_answer_polarityswitch(struct analog_pvt *p)
{
	if (analog_callbacks.answer_polarityswitch) {
		analog_callbacks.answer_polarityswitch(p->chan_pvt);
	}
}

static void analog_hangup_polarityswitch(struct analog_pvt *p)
{
	if (analog_callbacks.hangup_polarityswitch) {
		analog_callbacks.hangup_polarityswitch(p->chan_pvt);
	}
}

static int analog_dsp_set_digitmode(struct analog_pvt *p, enum analog_dsp_digitmode mode)
{
	if (analog_callbacks.dsp_set_digitmode) {
		return analog_callbacks.dsp_set_digitmode(p->chan_pvt, mode);
	}
	return -1;
}

static void analog_cb_handle_dtmf(struct analog_pvt *p, struct ast_channel *ast, enum analog_sub analog_index, struct ast_frame **dest)
{
	if (analog_callbacks.handle_dtmf) {
		analog_callbacks.handle_dtmf(p->chan_pvt, ast, analog_index, dest);
	}
}

static int analog_wink(struct analog_pvt *p, enum analog_sub index)
{
	if (analog_callbacks.wink) {
		return analog_callbacks.wink(p->chan_pvt, index);
	}
	return -1;
}

static int analog_has_voicemail(struct analog_pvt *p)
{
	if (analog_callbacks.has_voicemail) {
		return analog_callbacks.has_voicemail(p->chan_pvt);
	}
	return -1;
}

static int analog_is_dialing(struct analog_pvt *p, enum analog_sub index)
{
	if (analog_callbacks.is_dialing) {
		return analog_callbacks.is_dialing(p->chan_pvt, index);
	}
	return -1;
}

/*!
 * \internal
 * \brief Attempt to transfer 3-way call.
 *
 * \param p Analog private structure.
 *
 * \note On entry these locks are held: real-call, private, 3-way call.
 * \note On exit these locks are held: real-call, private.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
static int analog_attempt_transfer(struct analog_pvt *p)
{
	struct ast_channel *owner_real;
	struct ast_channel *owner_3way;
	enum ast_transfer_result xfer_res;
	int res = 0;

	owner_real = ast_channel_ref(p->subs[ANALOG_SUB_REAL].owner);
	owner_3way = ast_channel_ref(p->subs[ANALOG_SUB_THREEWAY].owner);

	ast_verb(3, "TRANSFERRING %s to %s\n",
		ast_channel_name(owner_3way), ast_channel_name(owner_real));

	ast_channel_unlock(owner_real);
	ast_channel_unlock(owner_3way);
	analog_unlock_private(p);

	xfer_res = ast_bridge_transfer_attended(owner_3way, owner_real);
	if (xfer_res != AST_BRIDGE_TRANSFER_SUCCESS) {
		ast_softhangup(owner_3way, AST_SOFTHANGUP_DEV);
		res = -1;
	}

	/* Must leave with these locked. */
	ast_channel_lock(owner_real);
	analog_lock_private(p);

	ast_channel_unref(owner_real);
	ast_channel_unref(owner_3way);

	return res;
}

static int analog_update_conf(struct analog_pvt *p)
{
	int x;
	int needconf = 0;

	/* Start with the obvious, general stuff */
	for (x = 0; x < 3; x++) {
		/* Look for three way calls */
		if ((p->subs[x].allocd) && p->subs[x].inthreeway) {
			if (analog_callbacks.conf_add) {
				analog_callbacks.conf_add(p->chan_pvt, x);
			}
			needconf++;
		} else {
			if (analog_callbacks.conf_del) {
				analog_callbacks.conf_del(p->chan_pvt, x);
			}
		}
	}
	ast_debug(1, "Updated conferencing on %d, with %d conference users\n", p->channel, needconf);

	if (analog_callbacks.complete_conference_update) {
		analog_callbacks.complete_conference_update(p->chan_pvt, needconf);
	}
	return 0;
}

struct ast_channel * analog_request(struct analog_pvt *p, int *callwait, const struct ast_channel *requestor)
{
	struct ast_channel *ast;

	ast_debug(1, "%s %d\n", __FUNCTION__, p->channel);
	*callwait = (p->owner != NULL);

	if (p->owner) {
		if (analog_alloc_sub(p, ANALOG_SUB_CALLWAIT)) {
			ast_log(LOG_ERROR, "Unable to alloc subchannel\n");
			return NULL;
		}
	}

	analog_set_outgoing(p, 1);
	ast = analog_new_ast_channel(p, AST_STATE_RESERVED, 0,
		p->owner ? ANALOG_SUB_CALLWAIT : ANALOG_SUB_REAL, requestor);
	if (!ast) {
		analog_set_outgoing(p, 0);
	}
	return ast;
}

int analog_available(struct analog_pvt *p)
{
	int offhook;

	ast_debug(1, "%s %d\n", __FUNCTION__, p->channel);

	/* If do not disturb, definitely not */
	if (p->dnd) {
		return 0;
	}
	/* If guard time, definitely not */
	if (p->guardtime && (time(NULL) < p->guardtime)) {
		return 0;
	}

	/* If no owner definitely available */
	if (!p->owner) {
		offhook = analog_is_off_hook(p);

		/* TDM FXO card, "onhook" means out of service (no battery on the line) */
		if ((p->sig == ANALOG_SIG_FXSLS) || (p->sig == ANALOG_SIG_FXSKS) || (p->sig == ANALOG_SIG_FXSGS)) {
#ifdef DAHDI_CHECK_HOOKSTATE
			if (offhook) {
				return 1;
			}
			return 0;
#endif
		/* TDM FXS card, "offhook" means someone took the hook off so it's unavailable! */
		} else if (offhook) {
			ast_debug(1, "Channel %d off hook, can't use\n", p->channel);
			/* Not available when the other end is off hook */
			return 0;
		}
		return 1;
	}

	/* If it's not an FXO, forget about call wait */
	if ((p->sig != ANALOG_SIG_FXOKS) && (p->sig != ANALOG_SIG_FXOLS) && (p->sig != ANALOG_SIG_FXOGS)) {
		return 0;
	}

	if (!p->callwaiting) {
		/* If they don't have call waiting enabled, then for sure they're unavailable at this point */
		return 0;
	}

	if (p->subs[ANALOG_SUB_CALLWAIT].allocd) {
		/* If there is already a call waiting call, then we can't take a second one */
		return 0;
	}

	if ((ast_channel_state(p->owner) != AST_STATE_UP) &&
	    ((ast_channel_state(p->owner) != AST_STATE_RINGING) || p->outgoing)) {
		/* If the current call is not up, then don't allow the call */
		return 0;
	}
	if ((p->subs[ANALOG_SUB_THREEWAY].owner) && (!p->subs[ANALOG_SUB_THREEWAY].inthreeway)) {
		/* Can't take a call wait when the three way calling hasn't been merged yet. */
		return 0;
	}
	/* We're cool */
	return 1;
}

static int analog_stop_callwait(struct analog_pvt *p)
{
	p->callwaitcas = 0;
	if (analog_callbacks.stop_callwait) {
		return analog_callbacks.stop_callwait(p->chan_pvt);
	}
	return 0;
}

static int analog_callwait(struct analog_pvt *p)
{
	p->callwaitcas = p->callwaitingcallerid;
	if (analog_callbacks.callwait) {
		return analog_callbacks.callwait(p->chan_pvt);
	}
	return 0;
}

static void analog_set_callwaiting(struct analog_pvt *p, int callwaiting_enable)
{
	p->callwaiting = callwaiting_enable;
	if (analog_callbacks.set_callwaiting) {
		analog_callbacks.set_callwaiting(p->chan_pvt, callwaiting_enable);
	}
}

static void analog_set_cadence(struct analog_pvt *p, struct ast_channel *chan)
{
	if (analog_callbacks.set_cadence) {
		analog_callbacks.set_cadence(p->chan_pvt, &p->cidrings, chan);
	}
}

static void analog_set_dialing(struct analog_pvt *p, int is_dialing)
{
	p->dialing = is_dialing;
	if (analog_callbacks.set_dialing) {
		analog_callbacks.set_dialing(p->chan_pvt, is_dialing);
	}
}

static void analog_set_alarm(struct analog_pvt *p, int in_alarm)
{
	p->inalarm = in_alarm;
	if (analog_callbacks.set_alarm) {
		analog_callbacks.set_alarm(p->chan_pvt, in_alarm);
	}
}

static void analog_set_ringtimeout(struct analog_pvt *p, int ringt)
{
	p->ringt = ringt;
	if (analog_callbacks.set_ringtimeout) {
		analog_callbacks.set_ringtimeout(p->chan_pvt, ringt);
	}
}

static void analog_set_waitingfordt(struct analog_pvt *p, struct ast_channel *ast)
{
	if (analog_callbacks.set_waitingfordt) {
		analog_callbacks.set_waitingfordt(p->chan_pvt, ast);
	}
}

static int analog_check_waitingfordt(struct analog_pvt *p)
{
	if (analog_callbacks.check_waitingfordt) {
		return analog_callbacks.check_waitingfordt(p->chan_pvt);
	}

	return 0;
}

static void analog_set_confirmanswer(struct analog_pvt *p, int flag)
{
	if (analog_callbacks.set_confirmanswer) {
		analog_callbacks.set_confirmanswer(p->chan_pvt, flag);
	}
}

static int analog_check_confirmanswer(struct analog_pvt *p)
{
	if (analog_callbacks.check_confirmanswer) {
		return analog_callbacks.check_confirmanswer(p->chan_pvt);
	}

	return 0;
}

static void analog_cancel_cidspill(struct analog_pvt *p)
{
	if (analog_callbacks.cancel_cidspill) {
		analog_callbacks.cancel_cidspill(p->chan_pvt);
	}
}

static int analog_confmute(struct analog_pvt *p, int mute)
{
	if (analog_callbacks.confmute) {
		return analog_callbacks.confmute(p->chan_pvt, mute);
	}
	return 0;
}

static void analog_set_pulsedial(struct analog_pvt *p, int flag)
{
	if (analog_callbacks.set_pulsedial) {
		analog_callbacks.set_pulsedial(p->chan_pvt, flag);
	}
}

static int analog_set_linear_mode(struct analog_pvt *p, enum analog_sub sub, int linear_mode)
{
	if (analog_callbacks.set_linear_mode) {
		/* Return provides old linear_mode setting or error indication */
		return analog_callbacks.set_linear_mode(p->chan_pvt, sub, linear_mode);
	}
	return -1;
}

static void analog_set_inthreeway(struct analog_pvt *p, enum analog_sub sub, int inthreeway)
{
	p->subs[sub].inthreeway = inthreeway;
	if (analog_callbacks.set_inthreeway) {
		analog_callbacks.set_inthreeway(p->chan_pvt, sub, inthreeway);
	}
}

int analog_call(struct analog_pvt *p, struct ast_channel *ast, const char *rdest, int timeout)
{
	int res, idx, mysig;
	char *c, *n, *l;
	char dest[256]; /* must be same length as p->dialdest */

	ast_debug(1, "CALLING CID_NAME: %s CID_NUM:: %s\n",
		S_COR(ast_channel_connected(ast)->id.name.valid, ast_channel_connected(ast)->id.name.str, ""),
		S_COR(ast_channel_connected(ast)->id.number.valid, ast_channel_connected(ast)->id.number.str, ""));

	ast_copy_string(dest, rdest, sizeof(dest));
	ast_copy_string(p->dialdest, rdest, sizeof(p->dialdest));

	if ((ast_channel_state(ast) == AST_STATE_BUSY)) {
		ast_queue_control(p->subs[ANALOG_SUB_REAL].owner, AST_CONTROL_BUSY);
		return 0;
	}

	if ((ast_channel_state(ast) != AST_STATE_DOWN) && (ast_channel_state(ast) != AST_STATE_RESERVED)) {
		ast_log(LOG_WARNING, "analog_call called on %s, neither down nor reserved\n", ast_channel_name(ast));
		return -1;
	}

	p->dialednone = 0;
	analog_set_outgoing(p, 1);