I want to unlock this At&T phone so that I can use my T-mobile sim. Help?

[nunya]

My grandma gave me her old phone so that I could replace my crappy phone. However I have T-mobile and she had Cingular (Now AT&T). It asks for a password when I turn on the phone and I don't know what it is and she doesn't know what it is.

How can I fix this? Can I fix this?

[geeth]

Ya sure only after unlocking the phone from AT&T network lock you can freely use it with t-mobile sim .You can easily unlock your phone using sites like MobileUnlockSolutions.com here they are rendering network unlock code for all mobile models at reliable cost .You first check that whether the code is available for your mobile model ,country and network provider .If yes then pay for it and unlock your phone then freely use it with your t-mobile sim ...