Hi yes sure you can use samsung balackjack 2 mobile with t-mobile sim only if it is unlocked one .Else if the phone is locked to some other network provider then you can't use it with t-mobile until you unlock it ...You can easily unlock your phone using sites like OnlineGSMUnlock.com they are providing unlock code for all mobile models at reliable cost .You first verify that whether the code is available for your country and network provider .If yes then pay for it and unlock your phone .