SIM lock:

A SIM lock, Network Lock, CARRIER LOCK, IMEI LOCK or (master) subsidy lock serves as a technical constraint built into GSM and CDMA mobile phone devices by manufacturers to be used by providers to limit the usage of these phones to particular locations and/or networks. This is in contrast to a phone (retrospectively called SIM-free or unlocked) which doesn't impose any SIM limitations.If the mobile phones were not locked, customers might possibly sign a contract with a particular company, acquire the marked down phone, then quit paying the monthly bill (thus breaking the agreement) and begin using the smartphone on a different mobile phone network or even sell the phone for a profit. SIM locking reduces this by prohibiting a change of network (using a new SIM).

Unlocking Technology:

A phone can be unlocked by entering a code provided by the network operator. Alternative mechanisms consist of software operating on the device or a computer attached to the handset, hardware devices that attach to the device or over-the-air by the carrier. Most of the time the unlock operation is permanent. The code required to remove all locks from a cell phone is known as the master code, network code key, or multi-lock code. If the device is network locked it will generally show one of the following messages: SIM network PIN blocked, Enter lock PIN.

Economics:

Quite often a SIM-locked mobile is offered for sale at a significantly lower cost than an unlocked one because the service provider expects income through its service. SIM locks are used on inexpensive (pay-as-you-go) devices, despite the fact that deals on higher end handsets need a subscription that delivers guaranteed income. Unlocked mobile phones have a much higher market value.

Unlocking Services:

A lot of organizations offer a imei phone unlocking service. This service calls for people that wish to unlock a mobile phone handset to give their IMEI number to a service supplier and quite often they will also request the country and service provider the mobile phone handset is locked to, sometimes sent by email or entered on their web site. The supplier will then provide (in return for a fee) an unlock code for the mobile phone.

Unlocking Service Providers:

Regrettably there are many of dodgy on line retailers active in the cell phone unlocking industry. Consequently it is advisable to ensure you use a reliable provider for such a service. Take the necessary precautions and investigate all prospective providers in advance of choosing to place an order. In the case of on line providers, ensure they publish their genuine organization name and associated registration details (every legit business must be lawfully registered with the official authorities for their country of origin) and make certain they provide a legitimate registered address and contact information on their website. In addition ensure that any payments made are done so by legitimate methods such as a recognised bank or financial institution using a debt or credit card, but never make payment via a direct transfer because this provides no fiancial protection. To aid with your search for a trustworthy supplier, we've supplied a checklist below (and in no specific order) of a few legitimate organizations currently offering such services.

Reputable Mobile Phone IMEI Unlocking Service Providers:

• Unlock Base
• Unlock River
• Cell Unlocker
• Mobile Unlocked
• DoctorSIM
• Unlock.Zone