diff --git a/core/sip/trans_layer.cpp b/core/sip/trans_layer.cpp
index 087b593e..5fee74e7 100644
--- a/core/sip/trans_layer.cpp
+++ b/core/sip/trans_layer.cpp
@@ -1696,19 +1696,28 @@ void _trans_layer::timer_expired(timer* t, trans_bucket* bucket, sip_trans* tr)
 	    sockaddr_storage sa;
 	    memset(&sa,0,sizeof(sockaddr_storage));
 
-	    //TODO: get the right port number 
-	    
 	    // get the next ip
 	    if(tr->msg->h_dns.next_ip(&sa) < 0){
 		tr->clear_timer(STIMER_M);
 		return;
 	    }
+
+	    //If a SRV record is involved, the port number
+	    // should have been set by h_dns.next_ip(...).
+	    if(!((sockaddr_in*)&sa)->sin_port){
+		//Else, we copy the old port number
+		((sockaddr_in*)&sa)->sin_port = ((sockaddr_in*)&tr->msg->remote_ip)->sin_port;
+	    }
+
+	    // copy the new address back
 	    memcpy(&tr->msg->remote_ip,&sa,sizeof(sockaddr_storage));
 
+
 	    // create new branch tag
 	    compute_branch((char*)(tr->msg->via_p1->branch.s+MAGIC_BRANCH_LEN),
 			   tr->msg->callid->value,tr->msg->cseq->value);
 
+	    // and re-send
 	    retransmit(tr->msg);
 
 	    // reset counter for timer A & E