There are two things to consider 1) SIM lock that ties a phone to a particular carrier. A Google phone wouldn't have a SIM lock unless it were subsidized by a

There are two things to consider 1) SIM lock that ties a phone to a particular carrier. A Google phone wouldn't have a SIM lock unless it were subsidized by a particular carrier. 2) GSM bands. The phone could be quad-band GSM and work on any 3G network. Some recent GSM handsets omit one of the four bands to prevent roaming inside the US between T-Mob and AT&T.