diff --git a/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_timers.c b/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_timers.c
index ff66cc6b41..10afc65bc9 100644
--- a/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_timers.c
+++ b/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_timers.c
@@ -56,21 +56,22 @@ void handle_isup_t35(void *userdata)
     ftdm_channel_t      *ftdmchan = sngss7_info->ftdmchan;
 
     /* now that we have the right channel...put a lock on it so no-one else can use it */
-    ftdm_mutex_lock(ftdmchan->mutex);
+    ftdm_channel_lock(ftdmchan);
 
+    /* Q.764 2.2.5 Address incomplete (T35 expiry action is hangup with cause 28 according to Table A.1/Q.764) */
     SS7_ERROR("[Call-Control] Timer 35 expired on CIC = %d\n", sngss7_info->circuit->cic);
 
     /* set the flag to indicate this hangup is started from the local side */
     sngss7_set_ckt_flag(sngss7_info, FLAG_LOCAL_REL);
 
     /* hang up on timer expiry */
-    ftdmchan->caller_data.hangup_cause = 28;
+    ftdmchan->caller_data.hangup_cause = FTDM_CAUSE_INVALID_NUMBER_FORMAT;
 
     /* end the call */
     ftdm_set_state(ftdmchan, FTDM_CHANNEL_STATE_CANCEL);
 
     /*unlock*/
-    ftdm_mutex_unlock(ftdmchan->mutex);
+    ftdm_channel_unlock(ftdmchan);
 
     SS7_FUNC_TRACE_EXIT(__FUNCTION__);
     return;
diff --git a/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_xml.c b/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_xml.c
index 2794eb497c..d7fc553e2f 100644
--- a/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_xml.c
+++ b/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_xml.c
@@ -2966,9 +2966,10 @@ static int ftmod_ss7_fill_in_ccSpan(sng_ccSpan_t *ccSpan)
 			g_ftdm_sngss7_data.cfg.isupCkt[x].t17		= ccSpan->t17;
 		}
 		if (ccSpan->t35 == 0) {
-			g_ftdm_sngss7_data.cfg.isupCkt[x].t17		= 170;
+			/* Q.764 2.2.5 Address incomplete (T35 is 15-20 seconds according to Table A.1/Q.764) */
+			g_ftdm_sngss7_data.cfg.isupCkt[x].t35		= 170;
 		} else {
-			g_ftdm_sngss7_data.cfg.isupCkt[x].t17		= ccSpan->t35;
+			g_ftdm_sngss7_data.cfg.isupCkt[x].t35		= ccSpan->t35;
 		}
 		if (ccSpan->tval == 0) {
 			g_ftdm_sngss7_data.cfg.isupCkt[x].tval		= 10;