I upgraded my mother in laws phone to a Photon for this purpose only. She's currently in Portugal using her Photon with a TMN sim card. Before she left, I changed the network to GSM only but once she turned it once, since there wasn't a sim card install, it switched over and began looking for Sprint service. The people working at the cell carrier didn't know what to do but I had my MIL call me and I walked them through setting it up once the TMN sim card was installed. She added a data plan to the sim card and she is able to surf the net and use Google Nav. I had her turn the phone off and then back on and it immediately connected to the TMN service. BTW, people working at TMN were totally blown away by the Photon since they've never seen it before.