This is a AT&T GSM basic phone for any gsm phone carriers in US and the rest of the world. It has been tested working on AT&T, T-Mobile, Lycamobile, Cricket, Straight Talk, H2O wireless, and MetroPCS in the United States; China Telecom, China Mobile, and China Unicom; and Roger in Canada. This phone supports GSM 850/900/1800/1900Mhz GSM and 850/1900Mhz HSPA. Please be advised that this unit will NOT work CDMA carriers such as Verizon, Virgin, and Sprint. You can just plug the card into the slot, wait 2-3 minutes to boot the phone, and you are in business. You do NOT need to talk to anyone to complete the activation! You need a full-size SIM card, i.e., the largest SIM card in terms of size. If your SIM card is not full-size card, you need to purchase an adapter to fit the SIM card slot. FVBusiness THANKS