While on vacation (outside of United States), my old phone from T-Mobile broke. So I bought a new phone here and I was wondering if I can just insert my old T-Mobile sim card and start using it. Do I need to unlock it or can I just use it? and If i need to unlock it, can I take it to the shop here which I bought the phone from to unlock it? or Do I have to wait until I am back in US and unlock it at a T-Mobile store?
Thanks for the help