Hi whether you want to use your sim card in another phone then you must first check that whether the phone is locked or unlocked one .If the phone is unlocked one then you can sure use it with any GSM sim .Else if the phone is locked to some other network provider then you can't use it with any other GSM sim until you unlock it .You can easily unlock your phone using sites like Unlocking4Free.com they are generating unlock code for some older mobile models at free of cost .Else if you want to unlock some other new model phone then visit sites like MobileUnlockSolutions.com they are providing unlock code for all mobile models at reliable cost .....