--- chan_sip.c	2007-07-06 10:47:16.000000000 +0000
+++ chan_sip.c	2007-07-06 14:31:23.000000000 +0000
@@ -12388,6 +12388,12 @@
 	peer->capability = global_capability;
 	peer->rtptimeout = global_rtptimeout;
 	peer->rtpholdtimeout = global_rtpholdtimeout;
+
+	if (peer->auth) {
+		clear_realm_authentication(peer->auth);
+		peer->auth = (struct sip_auth *) NULL;
+	}
+
 	while(v) {
 		if (handle_common_options(&peerflags, &mask, v)) {
 			v = v->next;