Index: b/apps/app_queue.c
===================================================================
--- a/apps/app_queue.c
+++ b/apps/app_queue.c
@@ -7669,6 +7669,7 @@ static struct queue_stasis_data *queue_s
 static void log_attended_transfer(struct queue_stasis_data *queue_data,
 		struct ast_attended_transfer_message *atxfer_msg)
 {
+	const char* cuid;
 	RAII_VAR(struct ast_str *, transfer_str, ast_str_create(32), ast_free);
 
 	if (!transfer_str) {
@@ -7695,7 +7696,13 @@ static void log_attended_transfer(struct
 		return;
 	}
 
-	ast_queue_log(queue_data->queue->name, queue_data->caller_uniqueid, queue_data->member->membername, "ATTENDEDTRANSFER", "%s|%ld|%ld|%d",
+	if (queue_data->caller_uniqueid) {
+		cuid = queue_data->caller_uniqueid;
+	} else {
+		cuid = "";
+	}
+
+	ast_queue_log(queue_data->queue->name, cuid, queue_data->member->membername, "ATTENDEDTRANSFER", "%s|%ld|%ld|%d",
 			ast_str_buffer(transfer_str),
 			(long) (queue_data->starttime - queue_data->holdstart),
 			(long) (time(NULL) - queue_data->starttime), queue_data->caller_pos);
