Samsung SCH-A790 / SCH-A795 / IP-A790

It may be their network, but it's my phone, and since these companies are not operating overseas, they're not losing any revenue, are they? Anyway, in answer to the question of whether these phones can be unlocked, rest assured that they can. There are services located on the web, who for a small fee will give you the code needed to unlock the phone so that you can purchase Sim cards when you are overseas. That way, you can make and receive calls for a reasonable price and not be ripped off to the tune of over $1/minute charged by the domestic carriers.