--- asterisk-1.6.2.14.orig/channels/chan_sip.c
+++ asterisk-1.6.2.14/channels/chan_sip.c
@@ -12978,7 +12978,15 @@ static int cb_extensionstate(char *conte
 {
 	struct sip_pvt *p = data;
 
-	sip_pvt_lock(p);
+	if( sip_pvt_trylock(p) ) {
+		/* This can deadlock when handle_statechange is active and we
+		 * also use ast_get_hint with the pvt locked, because lock ordering
+		 * differs, but cannot be changed.
+		 *
+		 * This error return gets handle_statechange to back off and try
+		 * again. */
+		return -1;
+	}
 
 	switch(state) {
 	case AST_EXTENSION_DEACTIVATED:	/* Retry after a while */
--- asterisk-1.6.2.14.orig/main/pbx.c
+++ asterisk-1.6.2.14/main/pbx.c
@@ -3918,12 +3918,30 @@ static int handle_statechange(void *data
 
 		/* For general callbacks */
 		AST_LIST_TRAVERSE(&statecbs, cblist, entry) {
-			cblist->callback(hint->exten->parent->name, hint->exten->exten, state, cblist->data);
+			while( cblist->callback(hint->exten->parent->name, hint->exten->exten, state, cblist->data) == -1 ) {
+				/* The callback failed to get a lock, unlock (but keep ref on hint[s]), sleep and retry */
+				ao2_unlock(hint);
+				ao2_unlock(hints);
+				ast_unlock_contexts();
+				usleep(1);
+				ast_rdlock_contexts();
+				ao2_lock(hints);
+				ao2_lock(hint);
+			}
 		}
 
 		/* For extension callbacks */
 		AST_LIST_TRAVERSE(&hint->callbacks, cblist, entry) {
-			cblist->callback(hint->exten->parent->name, hint->exten->exten, state, cblist->data);
+			while( cblist->callback(hint->exten->parent->name, hint->exten->exten, state, cblist->data) == -1 ) {
+				/* The callback failed to get a lock, unlock (but keep ref on hint[s]), sleep and retry */
+				ao2_unlock(hint);
+				ao2_unlock(hints);
+				ast_unlock_contexts();
+				usleep(1);
+				ast_rdlock_contexts();
+				ao2_lock(hints);
+				ao2_lock(hint);
+			}
 		}
 
 		hint->laststate = state;	/* record we saw the change */