Answer Base

I am a t-mobile phone user and will be going to thailand for a few months. when i am in bangkok, i want to buy a prepaid phone card. does anyone know if you you need to unlock your mobile phone before you can buy a prepaid card in thailand? if your phone is unlocked, then, when you are back in the uk, is there any problem with your current network?

Yes you need to unlock it with triple zero of ask the t mobile company in thailand, they would help you. there should not be a problem using in uk after using it in thailand.