T mobile blackberry help?!!?

So I have a blackberry and i was on a plan but from other people and they didnt pay their bill but i did whatever. and then they switched to att&t so they did have to pay the bill but apparently my phone was blocked because they didtn pay the bill if i switch the simcard because i got a new sim card and i havent used it yet. will it work? or will it still be blocked. Please help