How to say "Excuse me" on the phone?

[kycoo]

I was wondering if there is a polite and concise way to ask someone in Chinese to repeat himself while on the phone. Something akin to "Excuse me?" or "Sorry?". I always find myself saying either “什麼？” (which sounds rude) or something like “對不起，我沒聽清楚，可以再説一遍嗎？” (which is much too long and inconvenient).

Thanks in advance!