diff -pruN asterisk-trunk/channels/chan_zap.c asterisk-trunk-pc/channels/chan_zap.c
--- asterisk-trunk/channels/chan_zap.c	2007-03-13 09:51:57.697868238 +1100
+++ asterisk-trunk-pc/channels/chan_zap.c	2007-03-13 10:08:48.141006890 +1100
@@ -535,6 +535,7 @@ static struct zt_pvt {
 	unsigned int setup_ack:1;
 #endif
 	unsigned int use_smdi:1;		/* Whether to use SMDI on this channel */
+	unsigned int smdimatchterm:1;  /* Whether to match Zap channel number to SMDI desk terminal */
 	struct ast_smdi_interface *smdi_iface;	/* The serial port to listen for SMDI data on */
 
 	struct zt_distRings drings;
@@ -6379,7 +6380,23 @@ static void *ss_thread(void *data)
 #endif
 		/* check for SMDI messages */
 		if (p->use_smdi && p->smdi_iface) {
-			smdi_msg = ast_smdi_md_message_wait(p->smdi_iface, SMDI_MD_WAIT_TIMEOUT);
+			char *ptr1, *ptr2;
+			char cnbuf[BUFSIZ];
+
+			ast_copy_string(cnbuf, chan->name, BUFSIZ);
+
+			if (p->smdimatchterm) {
+				if ((ptr1 = strrchr(cnbuf, '/'))) {
+					ptr1++;
+					if ((ptr2 = strchr(ptr1, '-'))) {
+						*ptr2 = 0;
+						ast_log(LOG_DEBUG, "Looking for SMDI message in queue for MD terminal %d\n", atoi(ptr1));
+						smdi_msg = ast_smdi_md_message_for_term_wait(p->smdi_iface, atoi(ptr1), SMDI_MD_WAIT_TIMEOUT);
+					}
+				}
+			} else {
+				smdi_msg = ast_smdi_md_message_wait(p->smdi_iface, SMDI_MD_WAIT_TIMEOUT);
+			}
 
 			if (smdi_msg != NULL) {
 				ast_copy_string(chan->exten, smdi_msg->fwd_st, sizeof(chan->exten));
@@ -6390,7 +6407,7 @@ static void *ss_thread(void *data)
 					pbx_builtin_setvar_helper(chan, "_SMDI_VM_TYPE", "u");
 
 				if (option_debug)
-					ast_log(LOG_DEBUG, "Recieved SMDI message on %s\n", chan->name);
+					ast_log(LOG_DEBUG, "Found SMDI message for %s: TERM='%s', CALLST='%s', FWDST='%s'\n", chan->name, smdi_msg->mesg_desk_term, smdi_msg->calling_st, smdi_msg->fwd_st);
 			} else {
 				ast_log(LOG_WARNING, "SMDI enabled but no SMDI message present\n");
 			}
@@ -11875,6 +11892,8 @@ static int process_zap(struct zt_chan_co
 			confp->chan.use_smdi = ast_true(v->value);
 		} else if (!strcasecmp(v->name, "smdiport")) {
 			ast_copy_string(confp->smdi_port, v->value, sizeof(confp->smdi_port));
+		} else if (!strcasecmp(v->name, "smdiuseterm")) {
+			confp->chan.smdiuseterm = ast_true(v->value);
 		} else if (!strcasecmp(v->name, "transfer")) {
 			confp->chan.transfer = ast_true(v->value);
 		} else if (!strcasecmp(v->name, "canpark")) {
diff -pruN asterisk-trunk/include/asterisk/smdi.h asterisk-trunk-pc/include/asterisk/smdi.h
--- asterisk-trunk/include/asterisk/smdi.h	2007-03-13 09:52:09.366967272 +1100
+++ asterisk-trunk-pc/include/asterisk/smdi.h	2007-03-13 09:54:20.851349351 +1100
@@ -42,6 +42,8 @@
 #define SMDI_MAX_STATION_NUM_LEN 10
 #define SMDI_MAX_FILENAME_LEN 256
 
+#define MWI_PREFIX_LEN  50
+
 /*!
  * \brief An SMDI message waiting indicator message.
  *
@@ -99,13 +101,16 @@ struct ast_smdi_interface {
 	pthread_t thread;
 	struct termios mode;
 	int msdstrip;
+	char mwiprefix[MWI_PREFIX_LEN];
 	long msg_expiry;
 };
 
 
 /* MD message queue functions */
 struct ast_smdi_md_message *ast_smdi_md_message_pop(struct ast_smdi_interface *iface);
+struct ast_smdi_md_message *ast_smdi_md_message_for_term_pop(struct ast_smdi_interface *iface, int term);
 struct ast_smdi_md_message *ast_smdi_md_message_wait(struct ast_smdi_interface *iface, int timeout);
+struct ast_smdi_md_message *ast_smdi_md_message_for_term_wait(struct ast_smdi_interface *iface, int term, int timeout);
 void ast_smdi_md_message_putback(struct ast_smdi_interface *iface, struct ast_smdi_md_message *msg);
 
 /* MWI message queue functions */
diff -pruN asterisk-trunk/.lastclean asterisk-trunk-pc/.lastclean
--- asterisk-trunk/.lastclean	1970-01-01 10:00:00.000000000 +1000
+++ asterisk-trunk-pc/.lastclean	2007-03-13 10:20:51.681131948 +1100
@@ -0,0 +1 @@
+30
diff -pruN asterisk-trunk/res/res_smdi.c asterisk-trunk-pc/res/res_smdi.c
--- asterisk-trunk/res/res_smdi.c	2007-03-13 09:52:22.064163134 +1100
+++ asterisk-trunk-pc/res/res_smdi.c	2007-03-13 10:14:17.760042027 +1100
@@ -93,7 +93,7 @@ int ast_smdi_mwi_set(struct ast_smdi_int
 {
 	FILE *file;
 	int i;
-	
+
 	file = fopen(iface->name, "w");
 	if(!file) {
 		ast_log(LOG_ERROR, "Error opening SMDI interface %s (%s) for writing\n", iface->name, strerror(errno));
@@ -107,6 +107,9 @@ int ast_smdi_mwi_set(struct ast_smdi_int
 	for(i = 0; i < iface->msdstrip; i++)
 	   fprintf(file, "0");
 
+	if (iface->mwiprefix[0] != 0)
+	   fprintf(file, "%s", iface->mwiprefix);
+
 	fprintf(file, "%s!\x04", mailbox);
 	fclose(file);
 
@@ -125,7 +128,7 @@ int ast_smdi_mwi_unset(struct ast_smdi_i
 {
 	FILE *file;
 	int i;
-	
+
 	file = fopen(iface->name, "w");
 	if(!file) {
 		ast_log(LOG_ERROR, "Error opening SMDI interface %s (%s) for writing\n", iface->name, strerror(errno));
@@ -139,6 +142,9 @@ int ast_smdi_mwi_unset(struct ast_smdi_i
 	for(i = 0; i < iface->msdstrip; i++)
 	   fprintf(file, "0");
 
+	if (iface->mwiprefix[0] != 0)
+	   fprintf(file, "%s", iface->mwiprefix);
+
 	fprintf(file, "%s!\x04", mailbox);
 	fclose(file);
 
@@ -213,6 +219,53 @@ struct ast_smdi_md_message *ast_smdi_md_
 	return md_msg;
 }
 
+/*! 
+ * \brief Get the next SMDI message for terminal "term" from the queue.
+ * \param iface a pointer to the interface to use.
+ * \param term an integer to filter messages by desk terminal
+ *
+ * This function pulls the first unexpired message from the SMDI message queue
+ * on the specified interface that match desk terminal "term".  It will purge 
+ * all expired SMDI messages before returning.
+ *
+ * \return the next SMDI message, or NULL if there were no pending messages.
+ */
+struct ast_smdi_md_message *ast_smdi_md_message_for_term_pop(struct ast_smdi_interface *iface, int term)
+{
+	struct ast_smdi_md_message *md_msg = NULL;
+	struct timeval now;
+	long elapsed = 0;
+
+	/* purge old messages */
+	now = ast_tvnow();
+
+	ASTOBJ_CONTAINER_TRAVERSE(&iface->md_q, 1, {
+			ASTOBJ_RDLOCK(iterator);
+
+			elapsed = ast_tvdiff_ms(now, iterator->timestamp);
+
+			if (elapsed > iface->msg_expiry) {
+				/* found an expired message */
+				ASTOBJ_MARK(iterator);
+				ast_log(LOG_NOTICE, "Purged expired message from %s SMDI MD message queue.  Message was %ld milliseconds too old.\n",
+					iface->name, elapsed - iface->msg_expiry);
+			} else {
+				if (term == atoi(iterator->mesg_desk_term)) {
+					ASTOBJ_MARK(iterator);
+					md_msg = ASTOBJ_REF(iterator);
+					ASTOBJ_UNLOCK(iterator);
+					break;
+				}
+			}
+
+			ASTOBJ_UNLOCK(iterator);
+	} );
+
+	ASTOBJ_CONTAINER_PRUNE_MARKED(&iface->md_q, ast_smdi_md_message_destroy);
+
+	return md_msg;
+}
+
 /*!
  * \brief Get the next SMDI message from the queue.
  * \param iface a pointer to the interface to use.
@@ -245,6 +298,39 @@ extern struct ast_smdi_md_message *ast_s
 }
 
 /*!
+ * \brief Get the next SMDI message from the queue
+ * \param iface a pointer to the interface to use.
+ * \param term an integer to filter messages by desk terminal
+ * \param timeout the time to wait before returning in milliseconds.
+ *
+ * This function pulls a message from the SMDI message queue on the specified
+ * interface.  If no message is available this function will wait the specified
+ * amount of time before returning.  Will only pop messages that match the
+ * terminal "term".
+ *
+ * \return the next SMDI message, or NULL if there were no pending messages and
+ * the timeout has expired.
+ */
+extern struct ast_smdi_md_message *ast_smdi_md_message_for_term_wait(struct ast_smdi_interface *iface, int term, int timeout)
+{
+	struct timeval start;
+	long diff = 0;
+	struct ast_smdi_md_message *msg;
+
+	start = ast_tvnow();
+	while (diff < timeout) {
+
+		if ((msg = ast_smdi_md_message_for_term_pop(iface, term)))
+			return msg;
+
+		/* check timeout */
+		diff = ast_tvdiff_ms(ast_tvnow(), start);
+	}
+
+	return (ast_smdi_md_message_for_term_pop(iface, term));
+}
+
+/*!
  * \brief Get the next SMDI message from the queue.
  * \param iface a pointer to the interface to use.
  *
@@ -414,7 +500,7 @@ static void *smdi_read(void *iface_p)
 				md_msg->timestamp = ast_tvnow();
 				ast_smdi_md_message_push(iface, md_msg);
 				if (option_debug)
-					ast_log(LOG_DEBUG, "Recieved SMDI MD message on %s\n", iface->name);
+					ast_log(LOG_DEBUG, "Received SMDI MD message on %s: TERM='%s', CALLST='%s', FWDST='%s'\n", iface->name, md_msg->mesg_desk_term, md_msg->calling_st, md_msg->fwd_st);
 				
 				ASTOBJ_UNREF(md_msg, ast_smdi_md_message_destroy);
 
@@ -458,7 +544,7 @@ static void *smdi_read(void *iface_p)
 				mwi_msg->timestamp = ast_tvnow();
 				ast_smdi_mwi_message_push(iface, mwi_msg);
 				if (option_debug)
-					ast_log(LOG_DEBUG, "Recieved SMDI MWI message on %s\n", iface->name);
+					ast_log(LOG_DEBUG, "Received SMDI MWI message on %s: FWDST='%s', CAUSE='%s'\n", iface->name, mwi_msg->fwd_st, mwi_msg->cause);
 				
 				ASTOBJ_UNREF(mwi_msg, ast_smdi_mwi_message_destroy);
 			} else {
@@ -531,6 +617,7 @@ static int smdi_load(int reload)
 	int stopbits = 0;              /* One stop bit */
 	
 	int msdstrip = 0;              /* strip zero digits */
+	char mwiprefix[MWI_PREFIX_LEN];
 	long msg_expiry = SMDI_MSG_EXPIRY_TIME;
 	
 	conf = ast_config_load(config_file);
@@ -551,6 +638,8 @@ static int smdi_load(int reload)
 	if (reload)
 		ASTOBJ_CONTAINER_MARKALL(&smdi_ifaces);
 
+	mwiprefix[0] = 0;
+
 	for (v = ast_variable_browse(conf, "interfaces"); v; v = v->next) {
 		if (!strcasecmp(v->name, "baudrate")) {
 			if (!strcasecmp(v->value, "9600"))
@@ -573,6 +662,16 @@ static int smdi_load(int reload)
 				ast_log(LOG_NOTICE, "Invalid msdstrip value in %s (line %d), using default\n", config_file, v->lineno);
 				msdstrip = 0;
 			}
+		} else if (!strcasecmp(v->name, "mwiprefix")) {
+			char *p;
+			int parsed = 1;
+			for (p = v->value; *p != 0; p++)
+				if (!isdigit(*p))
+					parsed = 0;
+			if (parsed) {
+				strncpy(mwiprefix, v->value, MWI_PREFIX_LEN);
+			} else
+				ast_log(LOG_NOTICE, "Invalid MWI prefix value '%s' in %s (line %d)\n", v->value, config_file, v->lineno);
 		} else if (!strcasecmp(v->name, "msgexpirytime")) {
 			if (!sscanf(v->value, "%ld", &msg_expiry)) {
 				ast_log(LOG_NOTICE, "Invalid msgexpirytime value in %s (line %d), using default\n", config_file, v->lineno);
@@ -675,6 +774,9 @@ static int smdi_load(int reload)
 			/* set the msdstrip */
 			iface->msdstrip = msdstrip;
 
+			/* set the mwi prefix (added before mbox extension for outgoing MWI) */
+			strncpy(iface->mwiprefix, mwiprefix, MWI_PREFIX_LEN);
+
 			/* set the message expiry time */
 			iface->msg_expiry = msg_expiry;