Your phone must use SIM cards (not CDMA only)
Your phone must be unlocked (i.e. not programmed to only work with your original carrier’s network)
Your phone must be a 3G (UMTS/HSDPA) phone, operating on a minimum dual-band frequency of 850/2100.
Confused? Try this: Go to your phone manual or an online site (we recommend GSM Arena), and look up your phone model.