--- asterisk-1.6.2.11-rc1/channels/chan_sip.c.orig	2010-07-24 22:03:22.000000000 -0400
+++ asterisk-1.6.2.11-rc1/channels/chan_sip.c	2010-07-24 22:05:06.000000000 -0400
@@ -14015,7 +14015,7 @@
 }
 
 /*! \brief Validate device authentication */
-static enum check_auth_result check_peer_ok(struct sip_pvt *p, char *of,
+static enum check_auth_result check_peer_ok(struct sip_pvt *p, char *of, char *domain,
 	struct sip_request *req, int sipmethod, struct sockaddr_in *sin,
 	struct sip_peer **authpeer,
 	enum xmittype reliable,
@@ -14031,8 +14031,16 @@
 	 	*/
 		peer = find_peer(of, NULL, TRUE, FINDALLDEVICES, FALSE, 0);
 	} else {
-		/* First find devices based on username (avoid all type=peer's) */
-		peer = find_peer(of, NULL, TRUE, FINDUSERS, FALSE, 0);
+		/* Make sure the device is from a local domain */
+		if (AST_LIST_EMPTY(&domain_list) || check_sip_domain(domain, NULL, 0)) {
+			/* First find devices based on username (avoid all type=peer's) */
+			peer = find_peer(of, NULL, TRUE, FINDUSERS, FALSE, 0);
+		}
+		else {
+			if(debug)
+				ast_verbose("Unknown peer from domain %s\n", domain);
+			peer = NULL;
+		}
 
 		/* Then find devices based on IP */
 		if (!peer) {
@@ -14271,7 +14279,7 @@
 		}
 	}
 
-	res = check_peer_ok(p, of, req, sipmethod, sin,
+	res = check_peer_ok(p, of, domain, req, sipmethod, sin,
 			authpeer, reliable, rpid_num, calleridname, uri2);
 	if (res != AUTH_DONT_KNOW)
 		return res;