What is a Carrier Lock

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SIM lock:

A SIMLOCK, NETWORK LOCK, carrier lock, imei-lock or (Master) SUBSIDY lock is a technical constraint built into GSM and CDMA mobile phone devices by producers for use by service providers to limit the use of these phones to a particular locations and/or networks. This is in comparison with a mobile phone (retrospectively called SIM-free or unlocked) that does not impose any SIM constraints.

Unlocking Technology:

A handset can be unlocked simply by entering a code supplied by the service operator. Different mechanisms consist of software running on the device or a computer connected to the device, hardware devices that connect to the device or over-the-air by the service provider. More often than not the unlock procedure is permanent. The code required to remove all locks from a phone is known as the master code, network code key, or multi-lock code. Generally if the device is network locked it will generally display one of these messages: SIM network PIN blocked, Enter lock PIN.


On many occasions a SIM-locked phone is offered at a considerably lower cost than an unlocked one simply because the company plans income thru its service. SIM locks are used on less expensive (pay-as-you-go) handsets, while discounts on more costly handsets demand a subscription which offers guaranteed income. Unlocked devices have a better market value.

Unlocking Services:

A few organizations provide a carrier unlocking service . This service calls for those people who want to unlock a mobile phone handset to give their IMEI number to a service supplier and in most cases they will also need the country and network the handset is locked to, either sent via email or submitted on their web-site. The company will then supply (in return for a fee) an unlock code for the mobile phone handset.

Unlocking Service Providers:

Regrettably there are many of dodgy online retailers working in the cell-phone carrier unlocking industry. Consequently it is advisable to be sure you locate a reliable supplier for these services. To aid with a search for a reputable company, we have provided a list below (and in no specific order) of several genuine organizations currently offering such services.

Reputable Mobile Phone IMEI Unlocking Service Providers: