What is a Network Lock?

From EjWiki

SIM lock: A SIM-LOCK, Network-Lock, Carrier Lock, IMEI LOCK or (Master) subsidy lock is actually a technical limit built into GSM and CDMA mobile devices by manufacturers to be used by service providers to limit the usage of these phones to particular countries and/or networks. This is in comparison with a phone (retrospectively called SIM-free or unlocked) which doesn't impose any SIM restrictions.

Unlocking Technology: A smartphone can be unlocked by entering a code supplied by the network operator. Alternative mechanisms include software operating on the handset or a computer or laptop attached to the phone, hardware devices that attach to the mobile or over-the-air by the service provider. Usually the unlock procedure is permanent. The code needed to do away with all locks from a smartphone is referred to as the master code, network code key, or multi-lock code. If the device is carrier locked it will typically show one of the following messages: SIM network PIN blocked, Enter lock PIN.

Economics: Most of the time a SIM-locked mobile is offered for sale at a substantially lower price than an unlocked one mainly because the supplier anticipates income thru its service. SIM locks are currently employed on less expensive (pay-as-you-go) mobile phones, though discounts on higher priced handsets need a subscription which offers guaranteed income. Unlocked phones have a a lot higher market value.

Unlocking Services: Some companies provide a online unlocking service. This service requires those people who would like to unlock a mobile phone handset to give their IMEI number to a service supplier and frequently they will also require the country and cellular network the handset is locked to, either sent via email or submitted on their web-site. The supplier will then provide (in return for a fee) an unlock code for the mobile phone.

Unlocking Service Providers: Disappointingly there are lots of dodgy on-line retailers working in the cellphone carrier unlocking industry. As a result it is recommended to be sure you find a reputable provider for such a service. Do your due diligence and investigate any prospective retailers before choosing to submitting an order. In the case of on line suppliers, ensure they publish their formal company name and matching registration details (every legitimate business must be legally registered with all the official governing bodies for their country of origin) and ensure they supply a genuine listed address and contact information on their web-site. Furthermore ensure that any payments made are through legitimate sources as in a recognized bank or financial institution using a debt or credit card, but do not ever make payment via a direct transfer since this provides no fiancial protection. To assist with the search for a reputable service provider, we have supplied a list just below (and in no particular order) of several legitimate organisations currently offering such services.

Reputable Mobile Phone IMEI Unlocking Service Providers: Unlock BaseUnlock RiverCell UnlockerMobile UnlockedDoctorSIMUnlock.Zone