Take the Shackles Off Your Cellphone
Stuck with a relatively new cell phone that’s tied to a provider you no longer have a contract with? Bummed about having to go out and buy, and reprogram, yet another new phone? Feeling like this is all so “ball and chain?”
… it doesn’t have to be so. If you have a GSM phone, you can unlock it and switch to any GSM network carrier (the big three are AT&T, Cingular and T-Mobile). You can also take an unlocked phone overseas (most of the world uses GSM) and use it on a local network to avoid paying for international roaming, or even buy a European phone (they tend to be ahead of us in cell tech) and use it here. Have an old phone lying around? Unlock it and keep it as a spare.
The key is the subscriber identity module, or SIM, card, which stores the essential information–carrier, number, contacts–in all GSM phones. So once your phone is unlocked, switching carriers or phones simply means popping in a new SIM (available at any cell store here or overseas).