What is a SIM lock

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SIM lock:

A SIM-Lock, network lock, Carrier-Lock, imei lock or (master) subsidy lock is a technical restriction built into GSM and CDMA smartphones by producers for use by carrier networks to limit using these phones to particular countries and/or networks. This is unlike a phone (retrospectively called SIM-free or unlocked) that does not enforce any SIM limitations.SIM locking is very common if subsidized phones are sold with pre-paid contracts. It is important to note, however, that this technology accompanying with the mobile phone has to be compatible with the technology being employed by the network carrier. A GSM phone is only going to work with a GSM carrier and will not function on a CDMA service. Likewise, a CDMA cell phone is only going to work with a CDMA network and is not going to work on a GSM network. Note that more recent (2013 and newer) pricier cell phones are capable of supporting both CDMA and GSM technologies, allowing consumers to utilize their smart phones on pretty much any network.

Unlocking Technology:

A phone can be unlocked simply by entering a code supplied by the service operator. Alternative mechanisms incorporate software running on the device or a pc attached to the phone, hardware devices that attach to the phone or over-the-air by the service provider. Typically the unlock procedure is permanent. The code required to remove all locks from a smartphone is referred to as the master code, network code key, or multi-lock code. If the handset is network locked it will typically show one of these messages: SIM network PIN blocked, Enter lock PIN.


On many occasions a SIM-locked handset is offered for sale at a significantly reduced cost than an unlocked one mainly because the supplier anticipates income through its service. SIM locks are used on less expensive (pay-as-you-go) devices, though special discounts on more pricey handsets require a subscription that gives guaranteed income. Unlocked phones have a increased market value.

Unlocking Services:

Plenty of organizations offer a unlocking service . This service calls for all those that need to unlock a device to provide their IMEI number to a service supplier and in most cases they will also request the country and cellular network the handset is locked to, frequently sent through email or entered on their website. The company will then provide (at a cost to you) an unlock code for the handset.

Unlocking Service Providers:

Disappointingly there are a great deal of fraudulent sellers operating in the cellphone IMEI unlocking industry. Consequently it pays off to ensure you locate a genuine supplier for this service. To aid with the search for a legitimate supplier, we have provided a checklist just below (and in no particular order) of several genuine organizations currently offering such services.

Reputable Mobile Phone IMEI Unlocking Service Providers: