FS-4079 possible fix

src/mod/endpoints/mod_sofia/mod_sofia.c

@@ -2339,6 +2339,19 @@ static switch_status_t sofia_receive_message(switch_core_session_t *session, swi
 		break;
 
 	case SWITCH_MESSAGE_INDICATE_RESPOND:
+		{
+			int status = 0;
+
+			if (tech_pvt->nh && tech_pvt->nh->nh_ds && tech_pvt->nh->nh_ds->ds_sr && nua_server_request_is_pending(tech_pvt->nh->nh_ds->ds_sr)) {
+				status = tech_pvt->nh->nh_ds->ds_sr->sr_status;
+			}
+
+			if (status == 0 || status > 199 || tech_pvt->nh->nh_destroyed) {
+				switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(session), SWITCH_LOG_WARNING, "%s Cannot call respond on handle at status %d\n", 
+								  switch_channel_get_name(channel), status);
+				goto end_lock;
+			}
+
 			if (msg->numeric_arg || msg->string_arg) {
 				int code = msg->numeric_arg;
 				const char *reason = NULL;
@@ -2485,6 +2498,7 @@ static switch_status_t sofia_receive_message(switch_core_session_t *session, swi
 				}
 
 			}
+		}
 		break;
 	case SWITCH_MESSAGE_INDICATE_RINGING:
 		{