We've trained Virga to ring bells when she's got to go out. She doesn't have any indicators that she's about to pee either. We'd still have to make her go out every hour or so but we'd go to the back door and call her and then say "outside" and ring the bell. And then after a while we'd make her do it. We'd say "outside" and the minute she rang the bell we'd make a big ol' fuss over her and let her out. And when she went pee outside she'd get a treat. It took a while and she still has accidents if we don't hear the bells. But she'll ring the bells to be let out. We've come to distinguish the difference between her playing with the bells and actually needing to go out. The trick is just to be more stubborn than she is! She'll figure it out eventually.