If i put my at&t sim card in a tmobile phone, will it work?

Will it work so i can still call/text people? Please help! :)

Yes, provided both t-mobiles are of same country. If they are different country then there is a chance for the mobile to be locked. You need to unlock inorder to swap simcards. To unlock, I suggest you can approach Simpleunlocking.com and specify the country,locked network of phone and get the unlock along with free instructions.

You should unlock it inorder to swap simcards. I suggest you can approach Simpleunlocking.com and specify the country,locked network of phone.Based on the availability you can get the permanent unlock service along with free instructions.