diff --git a/pjsip/include/pjsip/sip_config.h b/pjsip/include/pjsip/sip_config.h
index 61d013cb8c..dbc3312c3b 100644
--- a/pjsip/include/pjsip/sip_config.h
+++ b/pjsip/include/pjsip/sip_config.h
@@ -1045,6 +1045,19 @@ PJ_INLINE(pjsip_cfg_t*) pjsip_cfg(void)
 #   define PJSIP_TSX_1XX_RETRANS_DELAY	60
 #endif
 
+/**
+ * Setting to determine if certain SIP UAS transaction, such as
+ * INVITE UAS tsx that hasn't been confirmed, is allowed to continue
+ * upon transport error. If disabled, the transaction will always be
+ * terminated, which is the default behavior prior to the introduction
+ * of this setting.
+ *
+ * Default: 1 (transaction will continue)
+ */
+#ifndef PJSIP_TSX_UAS_CONTINUE_ON_TP_ERROR
+#   define PJSIP_TSX_UAS_CONTINUE_ON_TP_ERROR 1
+#endif
+
 #define PJSIP_MAX_TSX_KEY_LEN		(PJSIP_MAX_URL_SIZE*2)
 
 /* User agent. */
diff --git a/pjsip/src/pjsip/sip_transaction.c b/pjsip/src/pjsip/sip_transaction.c
index f663c7f4b0..6affceb45e 100644
--- a/pjsip/src/pjsip/sip_transaction.c
+++ b/pjsip/src/pjsip/sip_transaction.c
@@ -137,6 +137,7 @@ static pj_time_val timeout_timer_val = { (64*PJSIP_T1_TIMEOUT)/1000,
 #define RETRANSMIT_TIMER	1
 #define TIMEOUT_TIMER		2
 #define TRANSPORT_ERR_TIMER	3
+#define TRANSPORT_DISC_TIMER	4
 
 /* Flags for tsx_set_state() */
 enum
@@ -1124,8 +1125,11 @@ static void tsx_timer_callback( pj_timer_heap_t *theap, pj_timer_entry *entry)
         return;
     }
 
-    if (entry->id == TRANSPORT_ERR_TIMER) {
-	/* Posted transport error event */
+    if (entry->id == TRANSPORT_ERR_TIMER || entry->id == TRANSPORT_DISC_TIMER)
+    {
+	/* Posted transport error/disconnection event */
+	pj_bool_t tp_disc = (entry->id == TRANSPORT_DISC_TIMER);
+
 	entry->id = 0;
 	if (tsx->state < PJSIP_TSX_STATE_TERMINATED) {
 	    pjsip_tsx_state_e prev_state;
@@ -1137,6 +1141,31 @@ static void tsx_timer_callback( pj_timer_heap_t *theap, pj_timer_entry *entry)
 	    /* Release transport as it's no longer working. */
 	    tsx_update_transport(tsx, NULL);
 
+#if PJSIP_TSX_UAS_CONTINUE_ON_TP_ERROR
+	    if (tp_disc && tsx->method.id == PJSIP_INVITE_METHOD &&
+	    	tsx->role == PJSIP_ROLE_UAS && tsx->status_code < 200 &&
+	    	!(tsx->transport_flag & TSX_HAS_PENDING_TRANSPORT) &&
+        	!(tsx->transport_flag & TSX_HAS_PENDING_DESTROY))
+#else
+	    PJ_UNUSED_ARG(tp_disc);
+	    if (0)
+#endif
+	    {
+	    	/* Upon transport disconnection event, if we receive
+	    	 * incoming INVITE and haven't responded with a final answer,
+	    	 * just return here and don't terminate the transaction,
+	    	 * in case that the library can switch to another working
+	    	 * transport.
+	     	 */
+	    	tsx->transport_flag = 0;
+           	tsx->addr_len = 0;
+            	tsx->res_addr.transport = NULL;
+            	tsx->res_addr.addr_len = 0;
+	    	
+	    	pj_grp_lock_release(tsx->grp_lock);
+	    	return;
+	    }
+
 	    if (tsx->status_code < 200) {
 		pj_str_t err;
 		char errmsg[PJ_ERR_MSG_SIZE];
@@ -2132,7 +2161,7 @@ static void tsx_tp_state_callback( pjsip_transport *tp,
 	if (tsx->state < PJSIP_TSX_STATE_COMPLETED) {
 	    tsx_cancel_timer(tsx, &tsx->timeout_timer);
 	    tsx_schedule_timer(tsx, &tsx->timeout_timer, &delay,
-			       TRANSPORT_ERR_TIMER);
+			       TRANSPORT_DISC_TIMER);
 	}
 	unlock_timer(tsx);
     }