What is a Carrier Lock

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SIM lock:

A SIM-Lock, Network-Lock, CARRIER-LOCK, imei lock or (master) subsidy lock is actually a technical constraint built into GSM and CDMA smartphones by manufacturers for use by carriers to limit the use of these phones to a particular countries and/or networks. This is contrary to a cell phone (retrospectively called SIM-free or unlocked) that does not impose any SIM restrictions.

Unlocking Technology:

Normally, a locked phone will show a message if a restricted SIM is used, asking for the unlock code. On modern phone models running Android os software, the cellphone is going to display a message stating “SIM network unlock PIN” or “Enter Network Lock Control Key” if it's 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”. Alternative devices may show varying messages including "Enter special code" or "Enter unlocking code," or in some circumstances the handset will probably show a message stating that it's locked. After a valid code is typed in, the device displays "Network unlocked” or “Network unlock successful”.


Most of the time a SIM-locked phone is available at a noticeably lower price than an unlocked one simply because the service provider is expecting income through its service. SIM locks are applied on less expensive (pay-as-you-go) units, though discounts on more pricey handsets demand a subscription which offers guaranteed income. Unlocked mobile phones have a higher market value.

Unlocking Services:

Quite a few businesses provide a carrier cell phone unlocking service . This service requires people that would like to unlock a mobile phone to supply their IMEI number to a unlocking company and often they will also require the country and network the mobile is locked to, frequently sent through email or entered on their web-site. The company will then supply (in return for a fee) the unlock code for the mobile.

Unlocking Service Providers:

Unfortunately there are many of fraudulent "businesses" operating in the smartphone carrier unlocking industry. Consequently it pays off to be sure you find a honest supplier for this service. To assist with the search for a trustworthy supplier, we've provided a checklist below (and in no specific order) of several legitimate organisations currently offering such services.

Reputable Mobile Phone IMEI Unlocking Service Providers: