What is a master SUBSIDY lock?
From EjWiki
SIM lock: A sim lock, NETWORK-LOCK, CARRIER-LOCK, imei-lock or (MASTER) SUBSIDY lock is a technical limitation built into GSM and CDMA smartphones by producers to be used by carrier networks to restrict using these phones to specific locations and/or networks. This is unlike a mobile phone (retrospectively called SIM-free or unlocked) that does not enforce any SIM constraints.Generally if the phones were not locked, owners may well sign an agreement with one particular organization, acquire the low priced phone, then stop paying the monthly payment (thus breaking the agreement) and start using the mobile phone on a different network or maybe sell the device for a profit. SIM locking curbs this by prohibiting a change of supplier (using a new SIM).
Unlocking Technology: A handset can be unlocked by entering a code supplied by the network operator. Alternative mechanisms contain software operating on the handset or a computer attached to the handset, hardware devices that connect to the device or over-the-air by the provider. Generally the unlock process is permanent. The code needed to do away with all locks from a mobile phone is known as the master code, network code key, or multi-lock code. Generally if the device is carrier locked it will usually show one of the following messages: SIM network PIN blocked, Enter lock PIN.
Economics: Mobile producers have economic incentives both to strengthen SIM lock protection (which placates network providers and allows exclusivity offers) and weaken it (widening a mobile phone's overall appeal to buyers that are usually not interested in the service provider that offers it). At the same time, making it very hard to unlock a device might possibly make it considerably less attractive to network service providers who have a legal liability to supply unlock codes for some handsets or in particular countries.
Unlocking Services: Certain companies offer a remote phone unlocking service. This service calls for all those that wish to unlock a mobile to provide their IMEI number to a unlocking company and quite often they will also need the country and network the device is locked to, often sent by email or submitted on their website. The supplier then will provide (once you have paid) a unlock code for the phone.
Unlocking Service Providers: Regrettably there are a lot of fraudulent service providers active in the cell phone unlocking industry. As a consequence it pays to be sure you use a trustworthy provider for this service. Do your due diligence and investigate all potential suppliers in advance of committing to submitting an order. In the case of on-line suppliers, make certain they provide their formal organization name and associated registration details (all authentic business should be lawfully registered with the official governing bodies within their country of origin) and ensure they supply a genuine listed address and contact information on their web site. In addition ensure that any payments made are done so thru legitimate methods as in a recognised bank or financial institution using a debt or credit card, but never make payment via a direct transfer because this offers no fiancial security. To assist with the search for a trustworthy company, we've provided a checklist beneath (and in no specific order) of several legitimate organizations currently offering such services.
