What is a sim-lock?
From EjWiki
SIM lock: A SIM-Lock, NETWORK-LOCK, CARRIER LOCK, imei lock or (Master) SUBSIDY lock is a technical constraint built into GSM and CDMA phones by manufacturers for use by carriers to restrict the usage of these phones to a particular locations and/or networks. This is unlike a phone (retrospectively called SIM-free or unlocked) which doesn't enforce any SIM restrictions.Unlocking a smartphone is practically universally legal. Additionally, it's legal for providers to force SIM locks for certain amounts of time, differing by region.
Unlocking Technology: A mobile phone can be unlocked simply by entering a code provided by the network operator. Alternative mechanisms incorporate software running on the handset or a computer or laptop attached to the device, hardware devices that attach to the phone or over-the-air by the service provider. Most of the time the unlock process is permanent. The code needed to eliminate all locks from a smartphone is referred to as the master code, network code key, or multi-lock code. Generally if the device is carrier locked it will typically show one of these messages: SIM network PIN blocked, Enter lock PIN.
Economics: Most of the time a SIM-locked phone is offered for sale at a noticeably lower cost than an unlocked one mainly because the supplier plans income via its service. SIM locks are currently employed on less expensive (pay-as-you-go) devices, whilst discounts on more costly handsets require a subscription which offers guaranteed income. Unlocked mobiles have a improved market value.
Unlocking Services: Lots of companies provide a unlocking service. This service requires people whom want to unlock a mobile phone to supply their IMEI number to a unlocking company and frequently they will also require the country and cellular network the mobile phone handset is locked to, either sent by email or submitted on their website. The supplier then will provide (for a fee) the unlock code for the mobile.
Unlocking Service Providers: Unfortunately there are a lot of dodgy online retailers active in the cell phone carrier unlocking industry. Consequently it is advisable to be sure you find a reputable provider for such a service. Take the necessary precautions and investigate any potential retailers before choosing to submitting an order. In the case of on-line suppliers, make certain they specify their official business name and matching registration details (every authentic enterprise must be legally registered with all the official authorities within their country of origin) and ensure they supply a genuine registered address and contact information on their web-site. Furthermore ensure that any payments made are through legitimate sources such as a recognized bank or financial institution using a debt or credit card, but do not ever make payment via a direct transfer since this offers no fiancial safeguards. To assist with a search for a reputable service provider, we've provided a checklist beneath (and in no particular order) of several legit organisations currently offering such services.
Reputable Mobile Phone IMEI Unlocking Service Providers: Unlock.ZoneUnlock BaseUnlock RiverCell UnlockerMobile UnlockedDoctorSIM
