What is an IMEI ?
The IMEI (i.e. International Mobile Equipment Identity) number is used by a GSM network to identify devices attempting to connect to them and therefore can be used for stopping a stolen phone from accessing that network. It’s only used for identifying the device and has no permanent or semi-permanent relation to the subscriber. The IMEI number includes information on the origin, model, and serial number of the device.
IMEI = 14 digits + 1 Check Digit
IMEISV = 14 digits + 2 Digit Software Version Number
IMEI + SV = 14 digits + 1 Check Digit + 2 Digit Software Version Number
The format of the IMEI is AA-BBBBBB-CCCCCC-D, (15 Digits) although it may not always be displayed this way. The IMEISV drops the Luhn CD (i.e. Check Digit) in favour of an additional two digits for the SVN (i.e. Software Version Number), making the format AA-BBBBBB-CCCCCC-EE. The IMEI+SV incorporates both the check digit and the additional two digits for the Software Verison Number, making the format AA-BBBBBB-CCCCCC-D-EE.
What is a phone unlock code ?
An Unlock Code is a numeric string. When entered into a locked handset it releases the SIM lock restriction and allows the handset to be used on other GSM carriers.
What is a phone SIM lock ?
It is a software capability built into GSM phones by mobile phone manufacturers. Network providers use this to restrict the use of these phones to specific countries and network providers.
How do I know my phone is locked ?
Insert a SIM Card from a different carrier than the one your handset is using. When power up is complete the handset will display a message like those below if it SIM locked :- Enter Subsidy Code
– Enter Unlock Code
– Incorrect Sim Card
– Insert Correct Sim Card
– Invalid Smart Chip
– Phone Restricted
– Sim Network Unlock Code
– Sim Network Unlock Pin
– Special Code Required
– Wrong Sim Card
Why is my phone locked ?
When the purchase price of the mobile phone to the consumer is subsidized with revenue from subscriptions, operators must recoup this investment before a subscriber terminates service. In order to secure their investments, GSM network providers implements a software feature called SIM Lock on the handset to prevent usage outside their network. Such subsidies are worth more than several hundred US dollars and in that’s why carriers also charge an early termination fee; another form to recoup the subsidy investment.
Is it Legal to unlock my phone ?
The Digital Millennium Copyright Act, introduced an exemption on November 27, 2006 specifically permitting unlocking of cellular devices. The exemption was scheduled to expire on October 27, 2009, but was extended on an interim basis, because the Register of Copyrights had not yet completed its triennial review of DMCA exemptions. In July 2010, the Librarian of Congress extended the DMCA exemption for another 3 years.
Why should I unlock my phone ?
Unlocking your cell phone has multiple benefits : It increases the resell value and marketability of your phone by not restricting the resell to a specific carrier, it allows the handset to work worldwide (See What networks are compatible with my phone ?), it eliminates roaming charges by allowing you to switch to a local carrier in the local region.