Ya sure the sony ericsson G502 mobile will work freely with metro pcs sim only if it 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 .You can easily unlock your phone using sites like SimpleUnlocking.com they are rendering 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 your phone .