What does it mean for a phone to be "unlocked?" Put simply: It means you can use it on any carrier, as long as they support the type of wireless network as the phone. (Typically this means the GSM network, supported by Cingular/AT&T and T-Mobile in the U.S.) You'll also need a SIM card, which you can remove from your regular cell phone and put in the unlocked model. This is a very simple procedure, though you'll almost always need to remove the battery to get to the SIM card. Here are my picks for the best GSM phones that include a camera. (Note: the links may not always go to unlocked versions of the phone, but all are available in unlocked versions.)