As has been discussed to death elsewhere, the Photon 4G SIM slot is not locked -- only the CDMA provisioning. However, the radio is programmed not to associate with any U.S. GSM towers, no matter what SIM card you get. There is an ongoing effort in xda-developers to "fix" that; however, it seems pretty dicey to me. If this is what's important to you, you'd be better off selling the Photon and getting a phone more suitable for what you are really trying to do!