--- asterisk-1.4.17/channels/chan_zap.c	2007-12-20 21:08:42.000000000 +0100
+++ asterisk-1.4.17/channels/chan_zap_sendingcomplete.c	2008-01-17 15:28:25.000000000 +0100
@@ -8801,7 +8801,7 @@
 						pri->pvts[chanpos]->callingpres = e->ring.callingpres;
 					
 						/* Start PBX */
-						if (pri->overlapdial && ast_matchmore_extension(NULL, pri->pvts[chanpos]->context, pri->pvts[chanpos]->exten, 1, pri->pvts[chanpos]->cid_num)) {
+						if (!e->ring.complete && pri->overlapdial && ast_matchmore_extension(NULL, pri->pvts[chanpos]->context, pri->pvts[chanpos]->exten, 1, pri->pvts[chanpos]->cid_num)) {
 							/* Release the PRI lock while we create the channel */
 							ast_mutex_unlock(&pri->lock);
 							if (crv) {