What is a SIM and what is cell phone unlocking?
Regular cellular phone service providers use a serial number in your phone (ESN #) that is used by the cell phone company to identify who you are. The wireless service provider 'identifies' that a particular phone's serial number is your cell phone and knows to send cellular calls to that phone when someone dials your phone number.
A GSM cell telephone is not directly linked to you. Instead, it has a account card that can be removed , called a SIM card (subscriber information module card) and this SIM card has a serial number on it. This is what identifies you to the cellular provider.
The big difference about this is that you can put your SIM card into any compatible cell phone (mostly all modern GSM cell phones are compatible with the newer SIMs) and that phone will now act as your phone, because the cell phone service company sees your unique id or SIM inside it. It doesn't care that you've changed cell phones, it only cares is where to find your unique id # or SIM.
And now for the best part, in theory, you can put any SIM in any cell phone, the opposite is also true. Any phone can work with any SIM card. So, if you've already bought an expensive cell phone that you like and know how to use well, if you change from one GSM cellular company to another, you won't have to change cell phones. You can keep the phone you like, and all you need to do is replace the first company's SIM with your new phone service provider's SIM.
But, some cellular providers 'lock' their cell phones, basically, their phones have been programmed to work with SIMs only on their network. Reversing that programming - unlocking your phone so it can work with any SIM - is what this article is all about. See how to unlock your phone in the full article from Travelinsider. >>>>