Can someone tell me who a t-mobile phone is registered to if I give the ID information on the phone battery?

I found a phone and need to know who it belongs to. I called t-mobile but they won't give me the name of the person it belongs to. Does anyone work with tmobile who could help me out?|||Info on the battery will be of no use to anybody. Call some of the people in the address book or the call logs and try and find out who it belongs to that way or take it to a T-mobile store and give it to them and they can contact the owner