A:Answer You can just put your AT&T SIM card into the phone to "activate" it. In this modern age, "activation" basically means putting the SIM card into the phone, turning on the phone, and having the phone joining/running on the carrier network -- the phone should auto configure everything. You absolutely can switch to a different carrier and put in a different SIM card. Activation should not lock any unlocked phone into AT&T, or any carrier.
