I found an iphone 4 and i need to know if i can activate it with t mobile or att?

I found this iphone 4 and its look new and i myself have a crappy metro phone. I'm thinking of switching to tmobile or att or any other gsm carrier other there that takes sim cards. Like simple mobile or straight talk. But i dunno if i will b able to activate it. How do i know. Can i do it?

Found an iPhone 4? Don't you mean stole an iPhone 4?

As long as someone doesn't use the "Find my IPhone" app and shut the phone off, you should be able to use it. Surely you know someone with a GSM iPhone, just put their SIM card in it, it'll probably work.

TIYou can't and most likely the person that lost it probley called there carrier and reported there phone lost or stoling so noone will use it… You can try tho… Mabe you should try and find the owner to it by calling people in there contact list it could have been a busy moms phone and she left it down somewhere by accident and now she lost all her pictures you know.

You probably can't as whoever lost it would have had the phone service terminated. Even if they had it deactivated, and you place in another sim card, the phone's imei number has been banned.