--- asterisk-13.4.0.original/channels/sig_ss7.c	2015-06-04 16:20:51.000000000 +0300
+++ asterisk-13.4.0/channels/sig_ss7.c	2016-03-21 14:50:12.207114498 +0300
@@ -2002,8 +2002,19 @@
 					p->call_level = SIG_SS7_CALL_LEVEL_PROCEEDING;
 				}
 				sig_ss7_set_dialing(p, 0);
+				switch(e->acm.called_party_status_ind) {
+				case 0:
+					/* No indication */
+					if(e->acm.inband_available) {
+						ast_debug(1, "Queuing frame PROGRESS on CIC %d due inband available pattern.\n", p->cic);
+						sig_ss7_queue_control(linkset, chanpos, AST_CONTROL_PROGRESS);
+						p->progress = 1;
+						sig_ss7_open_media(p);
+					}
+					break;
+				case 1:
 				/* Send alerting if subscriber is free */
-				if (e->acm.called_party_status_ind == 1) {
+					{
 					if (p->call_level < SIG_SS7_CALL_LEVEL_ALERTING) {
 						p->call_level = SIG_SS7_CALL_LEVEL_ALERTING;
 					}
@@ -2014,6 +2025,10 @@
 					}
 					sig_ss7_queue_control(linkset, chanpos, AST_CONTROL_RINGING);
 				}
+					break;
+				default:
+					break;
+				}
 				p->echocontrol_ind = e->acm.echocontrol_ind;
 				sig_ss7_unlock_private(p);
 				break;