diff --git a/libs/openzap/mod_openzap/mod_openzap.c b/libs/openzap/mod_openzap/mod_openzap.c
index 88c75c2d9d..ff5a564d51 100644
--- a/libs/openzap/mod_openzap/mod_openzap.c
+++ b/libs/openzap/mod_openzap/mod_openzap.c
@@ -817,50 +817,57 @@ static switch_status_t channel_receive_message_b(switch_core_session_t *session,
 			
 	tech_pvt = (private_t *) switch_core_session_get_private(session);
 	assert(tech_pvt != NULL);
-	
+	assert(tech_pvt->zchan != NULL);
+
+	zap_mutex_lock(tech_pvt->zchan->mutex);	
+	if (tech_pvt->zchan->state == ZAP_CHANNEL_STATE_TERMINATING) {
+		zap_mutex_unlock(tech_pvt->zchan->mutex);	
+		return SWITCH_STATUS_SUCCESS;
+	}
+
 	switch (msg->message_id) {
 	case SWITCH_MESSAGE_INDICATE_RINGING:
 		{
 			if (switch_channel_test_flag(channel, CF_OUTBOUND)) {
-				zap_set_flag_locked(tech_pvt->zchan, ZAP_CHANNEL_PROGRESS);
+				zap_set_flag(tech_pvt->zchan, ZAP_CHANNEL_PROGRESS);
 			} else {
-				zap_set_state_locked_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_PROGRESS);
+				zap_set_state_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_PROGRESS);
 			}
 		}
 		break;
 	case SWITCH_MESSAGE_INDICATE_PROGRESS:
 		{
 			if (switch_channel_test_flag(channel, CF_OUTBOUND)) {
-				zap_set_flag_locked(tech_pvt->zchan, ZAP_CHANNEL_PROGRESS);
-				zap_set_flag_locked(tech_pvt->zchan, ZAP_CHANNEL_MEDIA);
+				zap_set_flag(tech_pvt->zchan, ZAP_CHANNEL_PROGRESS);
+				zap_set_flag(tech_pvt->zchan, ZAP_CHANNEL_MEDIA);
 			} else {
 				/* Don't skip messages in the ISDN call setup
 				 * TODO: make the isdn stack smart enough to handle that itself
 				 *       until then, this is here for safety...
 				 */
 				if (tech_pvt->zchan->state < ZAP_CHANNEL_STATE_PROGRESS) {
-					zap_set_state_locked_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_PROGRESS);
+					zap_set_state_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_PROGRESS);
 				}
-				zap_set_state_locked_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_PROGRESS_MEDIA);
+				zap_set_state_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_PROGRESS_MEDIA);
 			}
 		}
 		break;
 	case SWITCH_MESSAGE_INDICATE_ANSWER:
 		{
 			if (switch_channel_test_flag(channel, CF_OUTBOUND)) {
-				zap_set_flag_locked(tech_pvt->zchan, ZAP_CHANNEL_ANSWERED);
+				zap_set_flag(tech_pvt->zchan, ZAP_CHANNEL_ANSWERED);
 			} else {
 				/* Don't skip messages in the ISDN call setup
 				 * TODO: make the isdn stack smart enough to handle that itself
 				 *       until then, this is here for safety...
 				 */
 				if (tech_pvt->zchan->state < ZAP_CHANNEL_STATE_PROGRESS) {
-					zap_set_state_locked_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_PROGRESS);
+					zap_set_state_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_PROGRESS);
 				}
 				if (tech_pvt->zchan->state < ZAP_CHANNEL_STATE_PROGRESS_MEDIA) {
-					zap_set_state_locked_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_PROGRESS_MEDIA);
+					zap_set_state_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_PROGRESS_MEDIA);
 				}
-				zap_set_state_locked_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_UP);
+				zap_set_state_wait(tech_pvt->zchan, ZAP_CHANNEL_STATE_UP);
 			}
 		}
 		break;
@@ -868,6 +875,7 @@ static switch_status_t channel_receive_message_b(switch_core_session_t *session,
 		break;
 	}
 
+	zap_mutex_unlock(tech_pvt->zchan->mutex);	
 	return SWITCH_STATUS_SUCCESS;
 }
 
diff --git a/libs/openzap/src/include/openzap.h b/libs/openzap/src/include/openzap.h
index 2c7d132b3b..cfbf065b06 100644
--- a/libs/openzap/src/include/openzap.h
+++ b/libs/openzap/src/include/openzap.h
@@ -268,6 +268,26 @@
 /* The while(0) below throws a conditional expression is constant warning */
 #pragma warning(disable:4127) 
 #endif
+
+#define zap_wait_for_flag_cleared(obj, flag, time) 					\
+	do {										\
+		int __safety = time;							\
+		while(__safety-- && zap_test_flag(obj, flag)) { 			\
+			zap_mutex_unlock(obj->mutex);					\
+			zap_sleep(10);							\
+			zap_mutex_lock(obj->mutex);					\
+		}									\
+		if(!__safety) {								\
+			zap_log(ZAP_LOG_CRIT, "flag %d was never cleared\n", flag);	\
+		}									\
+	} while(0);
+
+#define zap_set_state_wait(obj, s) 						\
+	do {										\
+		zap_channel_set_state(obj, s, 0);					\
+		zap_wait_for_flag_cleared(obj, ZAP_CHANNEL_STATE_CHANGE, 100);     \
+	} while(0);
+
 #define zap_set_state_locked_wait(obj, s) 						\
 	do {										\
 		int __safety = 100;							\
@@ -280,16 +300,6 @@
 		}									\
 	} while(0);
 
-#define zap_locked_wait_for_flag_cleared(obj, flag, time) 						\
-	do {										\
-		int __safety = time;							\
-		while(__safety-- && zap_test_flag(obj, flag)) {	\
-			zap_sleep(10);							\
-		}									\
-		if(!__safety) {								\
-			zap_log(ZAP_LOG_CRIT, "flag %d was never cleared\n", flag);		\
-		}									\
-	} while(0);
 
 
 typedef enum {
diff --git a/libs/openzap/src/ozmod/ozmod_r2/ozmod_r2.c b/libs/openzap/src/ozmod/ozmod_r2/ozmod_r2.c
index 9683aa57b2..f911e67d95 100644
--- a/libs/openzap/src/ozmod/ozmod_r2/ozmod_r2.c
+++ b/libs/openzap/src/ozmod/ozmod_r2/ozmod_r2.c
@@ -166,7 +166,7 @@ static ZIO_CHANNEL_OUTGOING_CALL_FUNCTION(r2_outgoing_call)
 	zap_mutex_lock(zchan->mutex);
 
 	/* the channel may be down but the thread not quite done */
-	zap_locked_wait_for_flag_cleared(zchan, ZAP_CHANNEL_INTHREAD, 200);
+	zap_wait_for_flag_cleared(zchan, ZAP_CHANNEL_INTHREAD, 200);
 
 	if (zap_test_flag(zchan, ZAP_CHANNEL_INTHREAD)) {
 		zap_log(ZAP_LOG_ERROR, "%d:%d Yay! R2 outgoing call in channel that is already in thread.\n", 
@@ -217,7 +217,7 @@ static void zap_r2_on_call_init(openr2_chan_t *r2chan)
 	}
 
 	/* the channel may be down but the thread not quite done */
-	zap_locked_wait_for_flag_cleared(zchan, ZAP_CHANNEL_INTHREAD, 200);
+	zap_wait_for_flag_cleared(zchan, ZAP_CHANNEL_INTHREAD, 200);
 
 	if (zap_test_flag(zchan, ZAP_CHANNEL_INTHREAD)) {
 		zap_log(ZAP_LOG_ERROR, "Cannot handle request to start call in channel %d, already in thread!\n", 
diff --git a/libs/openzap/src/ozmod/ozmod_sangoma_boost/ozmod_sangoma_boost.c b/libs/openzap/src/ozmod/ozmod_sangoma_boost/ozmod_sangoma_boost.c
index 892094126e..4c4caffb9b 100644
--- a/libs/openzap/src/ozmod/ozmod_sangoma_boost/ozmod_sangoma_boost.c
+++ b/libs/openzap/src/ozmod/ozmod_sangoma_boost/ozmod_sangoma_boost.c
@@ -372,9 +372,9 @@ static ZIO_CHANNEL_REQUEST_FUNCTION(sangoma_boost_channel_request)
 	while(zap_running() && OUTBOUND_REQUESTS[r].status == BST_ACK) {
 		zap_sleep(1);
 		if (--sanity <= 0) {
-		status = ZAP_FAIL;
-		*zchan = NULL;
-		goto done;
+			status = ZAP_FAIL;
+			*zchan = NULL;
+			goto done;
 		}
 		//printf("WTF %d\n", sanity);
 	}
@@ -625,9 +625,11 @@ static void handle_call_start_nack(zap_span_t *span, sangomabc_connection_t *mco
 		if ((zchan = find_zchan(span, event, 1))) {
 			int r = 0;
 			assert(!zap_test_flag(zchan, ZAP_CHANNEL_OUTBOUND));
+	
+			zchan->call_data = (void*)event->event_id;
 
 			zap_mutex_lock(zchan->mutex);
-			zap_set_state_r(zchan, ZAP_CHANNEL_STATE_CANCEL, 0, r);
+			zap_set_state_r(zchan, ZAP_CHANNEL_STATE_TERMINATING, 0, r);
 			if (r == ZAP_STATE_CHANGE_SUCCESS) {
 				zchan->caller_data.hangup_cause = event->release_cause;
 			}
@@ -898,9 +900,7 @@ static int parse_sangoma_event(zap_span_t *span, sangomabc_connection_t *mcon, s
 	}
 
 	assert(event->call_setup_id <= MAX_REQ_ID);
-	
     switch(event->event_id) {
-
     case SIGBOOST_EVENT_CALL_START:
 		handle_call_start(span, mcon, (sangomabc_event_t*)event);
 		break;
@@ -992,14 +992,25 @@ static __inline__ void state_advance(zap_channel_t *zchan)
 			if (!zap_test_sflag(zchan, SFLAG_SENT_FINAL_MSG)) {
 				zap_set_sflag_locked(zchan, SFLAG_SENT_FINAL_MSG);
 
-				sangomabc_exec_command(mcon,
-							   zchan->physical_span_id-1,
-							   zchan->physical_chan_id-1,
-							   0,
-							   SIGBOOST_EVENT_CALL_STOPPED_ACK,
-							   0);
+				if (zchan->call_data && ((uint32_t)zchan->call_data == SIGBOOST_EVENT_CALL_START_NACK)) {
+					sangomabc_exec_command(mcon,
+									zchan->physical_span_id-1,
+									zchan->physical_chan_id-1,
+									0,
+									SIGBOOST_EVENT_CALL_START_NACK_ACK,
+									0);
+					
+				} else {
+					sangomabc_exec_command(mcon,
+									zchan->physical_span_id-1,
+									zchan->physical_chan_id-1,
+									0,
+									SIGBOOST_EVENT_CALL_STOPPED_ACK,
+									0);
+				}
 			}
 			zchan->sflags = 0;
+			zchan->call_data = NULL;
 			zap_channel_done(zchan);
 		}
 		break;
@@ -1103,20 +1114,6 @@ static __inline__ void state_advance(zap_channel_t *zchan)
 			}
 		}
 		break;
-	case ZAP_CHANNEL_STATE_CANCEL:
-		{
-			sig.event_id = ZAP_SIGEVENT_STOP;
-			status = sangoma_boost_data->signal_cb(&sig);
-			zap_set_state_locked(zchan, ZAP_CHANNEL_STATE_DOWN);
-			zap_set_sflag_locked(zchan, SFLAG_SENT_FINAL_MSG);
-			sangomabc_exec_command(mcon,
-							   zchan->physical_span_id-1,
-							   zchan->physical_chan_id-1,
-							   0,
-							   SIGBOOST_EVENT_CALL_START_NACK_ACK,
-							   0);
-		}
-		break;
 	case ZAP_CHANNEL_STATE_TERMINATING:
 		{
 			sig.event_id = ZAP_SIGEVENT_STOP;
@@ -1476,7 +1473,7 @@ static zap_state_map_t boost_state_map = {
 			ZSD_INBOUND,
 			ZSM_UNACCEPTABLE,
 			{ZAP_CHANNEL_STATE_RING, ZAP_END},
-			{ZAP_CHANNEL_STATE_HANGUP, ZAP_CHANNEL_STATE_CANCEL, ZAP_CHANNEL_STATE_PROGRESS, ZAP_CHANNEL_STATE_PROGRESS_MEDIA, ZAP_END}
+			{ZAP_CHANNEL_STATE_HANGUP, ZAP_CHANNEL_STATE_TERMINATING, ZAP_CHANNEL_STATE_PROGRESS, ZAP_CHANNEL_STATE_PROGRESS_MEDIA,ZAP_END}
 		},
 		{
 			ZSD_INBOUND,
@@ -1487,14 +1484,14 @@ static zap_state_map_t boost_state_map = {
 		{
 			ZSD_INBOUND,
 			ZSM_UNACCEPTABLE,
-			{ZAP_CHANNEL_STATE_CANCEL, ZAP_CHANNEL_STATE_HANGUP_COMPLETE, ZAP_CHANNEL_STATE_TERMINATING, ZAP_END},
+			{ZAP_CHANNEL_STATE_HANGUP_COMPLETE, ZAP_CHANNEL_STATE_TERMINATING, ZAP_END},
 			{ZAP_CHANNEL_STATE_DOWN, ZAP_END},
 		},
 		{
 			ZSD_INBOUND,
 			ZSM_UNACCEPTABLE,
 			{ZAP_CHANNEL_STATE_PROGRESS, ZAP_CHANNEL_STATE_PROGRESS_MEDIA, ZAP_END},
-			{ZAP_CHANNEL_STATE_HANGUP, ZAP_CHANNEL_STATE_CANCEL, ZAP_CHANNEL_STATE_TERMINATING, ZAP_CHANNEL_STATE_UP, ZAP_CHANNEL_STATE_PROGRESS_MEDIA, ZAP_END},
+			{ZAP_CHANNEL_STATE_HANGUP, ZAP_CHANNEL_STATE_TERMINATING, ZAP_CHANNEL_STATE_UP, ZAP_CHANNEL_STATE_PROGRESS_MEDIA, ZAP_END},
 		},
 		{
 			ZSD_INBOUND,