diff -Nurp -x .svn a/channels/chan_sip.c b/channels/chan_sip.c
--- a/channels/chan_sip.c	2009-09-24 11:06:59.705767833 -0400
+++ b/channels/chan_sip.c	2009-09-24 11:08:38.615770162 -0400
@@ -11804,6 +11804,8 @@ static int transmit_register(struct sip_
 		if (!ast_strlen_zero(r->peername)) {
 			if (!(peer = find_peer(r->peername, NULL, 1, FINDPEERS, FALSE, 0))) {
 				ast_log(LOG_WARNING, "Could not find peer %s in transmit_register\n", r->peername);
+			} else {
+				p->peerauth = peer->auth;
 			}
 		}
 		ref_proxy(p, obproxy_get(p, peer)); /* it is ok to pass a NULL peer into obproxy_get() */