Ya sure you can use palm tero 750 mobile with t-mobile sim only if the phone is unlocked one else if the phone is locked to some other network provider then it wont accept any other GSM sim until you unlock it .You can easily unlock your phone using sites like ProUnlocking.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 country and network provider .If yes then pay for it and unlock the phone then freely use it with t-mobile or any other GSM sim ...