Cell phone unlocking is the process by which a mobile phone can be allowed to work on any carrier network. Customarily, North American cell phones are sold as “locked” phones, meaning that they will only work with one service carrier. For example, if you purchased a discounted phone from T-Mobile along with a two year plan, you will not be able to use your phone with another plan from a different service provider -- such as AT&T -- after your contract ends, because your phone is locked onto the Verizon network.
In many cases, this process is reversible. In fact, all cell phones are originally manufactured as unlocked phones, but service carriers will usually lock any phones they sell in order to charge roaming fees if the phone is ever used outside their network. Cell phone unlocking can be as easy as entering an unlocking code, or may involve some more complicated maneuvers involving external equipment. Some cell phones can’t be unlocked at all. Other unlocking services require that the user sends in the phone’s International Mobile Equipment Identity (IMEI), a unique number used to identify the phone's origin, model, and serial number, after which the unlocking code will be sent to the user. Still others require that the phone be sent in to their facilities for cell phone unlocking.
An unlocked cell phone provides the user with much more flexibility as to where and how they would like to use their phone. After unlocking, your phone could potentially be used in any part of the world, provided that the local carriers have compatible service on one of your phone’s frequency bands. However, cell phone unlocking does come with a price: many manufacturers will void a client’s warranty if third-party software was used to unlock the phone. Improper cell phone unlocking may also result in permanently locking the phone to a carrier, loss of personal data, or causing future incompatibilities with manufacturer-provided software upgrades.
If you want an unlocked cell phone without worries about permanently damaging your phone through the unlocking process, you can always buy an unlocked cell phone to begin, and then sign up with a carrier. Unlocked cell phones are available directly from the manufacturer, but also via online sites like eBay. These phones generally come from Asia or Europe, where the practice of locking cell phones is less common. They tend to be somewhat more expensive than phones sold by service carriers, because they do not come with any kind of plan agreement.