What is a CARRIER-LOCK?
From EjWiki
A SIM-LOCK, NETWORK LOCK, CARRIER-LOCK, IMEI LOCK or (MASTER) SUBSIDY lock serves as a technical limit built into GSM and CDMA cellular phones by producers to be used by carriers to restrict the use of these phones to particular locations and/or networks. This is not like a mobile phone (retrospectively called SIM-free or unlocked) which doesn't impose any SIM constraints.SIM locking is extremely common if subsidized phones are offered with prepay contracts. What is important to note, however, that this technology associated with the cellphone has to be compatible with the system being employed by the network carrier. A GSM cellphone will only operate with a GSM carrier and will never operate on a CDMA network. In the same way, a CDMA phone can only work with a CDMA network and will never work on a GSM network. Keep in mind that new (2013 and newer) advanced mobiles are capable of supporting both CDMA and GSM technologies, letting users to utilize their mobiles on nearly every network.
Unlocking Technology: Frequently, a locked mobile will show a message if a restricted SIM is used, asking for the unlock code. On recent phone models working on Android operating system software, the cell phone should show a message saying “SIM network unlock PIN” or “Enter Network Lock Control Key” if it is network locked. Windows phones are going to display the message, “This SIM card can only be used on specific networks. Contact your customer service center for the unlock code”. Several other devices may show varying messages such as "Enter special code" or "Enter unlocking code," or sometimes the handset will probably present a message stating it's locked. Once a valid code is keyed in, the phone will display "Network unlocked” or “Network unlock successful”.
Economics: Most of the time a SIM-locked device is offered at a considerably lower cost than an unlocked one because the supplier plans income through its service. SIM locks are used on inexpensive (pay-as-you-go) devices, whilst deals on higher priced handsets require a subscription that delivers guaranteed income. Unlocked phones have a a lot higher market value.
Unlocking Services: Plenty of organizations provide a on-line phone unlocking service. This service needs those people whom want to unlock a phone to give their IMEI number to a unlocking company and quite often they will also need the country and cellular network the handset is locked to, frequently sent through email or submitted on their website. The organization will then provide (in return for a fee) the unlock code for the mobile phone. For many brands for example Nokia and Samsung numerous services also provide unique remote-unlocking software with instructions, when a cable connection is required to remove the SIM lock at home. Such suppliers may well email the unlocking code or software that will remotely unlock the unit. The cost for unlocking a mobile phone may differ based on the mobile phone network its locked to and the handset model itself, as every unlock code is unique to each individual device.
Unlocking Service Providers: Regrettably there are a great deal of dodgy web sites operating in the cell-phone network unlocking industry. As a result it pays to be sure you use a genuine supplier for such a service.
