Is there anything shady about buying an unlocked cell phone on eBay? By “unlocked,” you’re referring to GSM phones that aren’t tied to a particular service provider and thus can be used anywhere in the world by inserting an appropriate SIM card.
You needn’t pony up for a new phone, however, to enjoy the benefits of unlocking. If you’ve got an old locked GSM phone lying around, try asking your carrier for the unlocking code. It’s AT&T policy, for example, to comply with unlock requests from customers whose contracts have expired. Link.