Sean is traveling out of the country and had his iPhone unlocked by AT&T. He's concerned because it doesn't really say it's unlocked. Leo says he can go to T-Mobile and tell them he's thinking of going with T-Mobile and if he could pop a SIM in to see if it works (TMobile will let users bring their own phone to the party).
Should he get a local SIM in Europe, though? Leo says that's a good idea. It's far cheaper and he'll get a local number. The real key with buying a local SIM is to make sure it works in all the countries he'd be traveling to.