freetdm: OPENZAP-151 --resolved SS7 ANM and REL message collision

libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_handle.c

@@ -584,6 +584,20 @@ ftdm_status_t handle_con_cfm(uint32_t suInstId, uint32_t spInstId, uint32_t circ
 
 		break;		
 	/**************************************************************************/
+	case FTDM_CHANNEL_STATE_HANGUP_COMPLETE:
+
+		/* already hangup complete, just ignore it */
+		/* 
+		 * i.e. collision REL & ANM
+		 * IAM ->
+		 * <- ACM
+		 * REL ->	<- ANM  (if REL gets processed first, ANM needs to be ignored)
+		 * <- RLC
+		 */
+		SS7_INFO_CHAN(ftdmchan,"[CIC:%d]Rx ANM/CON Ignoring it because we already hung up\n", sngss7_info->circuit->cic);
+
+		break;
+	/**************************************************************************/
 	default:	/* incorrect state...reset the CIC */
 
 		SS7_INFO_CHAN(ftdmchan,"[CIC:%d]Rx ANM/CON\n", sngss7_info->circuit->cic);