Common
SIM lock
Restriction built into a mobile phone
SIM lock
A SIM lock, simlock, network lock, carrier lock or (master) subsidy lock is a technical restriction built into GSM and CDMA mobile phones by mobile phone manufacturers for use by service providers to restrict the use of these phones to specific countries and/or networks. This is in contrast to a phone (retrospectively called SIM-free or unlocked) that does not impose any SIM restrictions. Generally phones can be locked to accept only SIM cards with certain International Mobile Subscriber Identities (IMSIs); IMSIs may be restricted by: Mobile country code (MCC; e.g., will only work with SIM issued in one country) Mobile network code (MNC; e.g., AT&T Mobility, T-Mobile, Vodafone, Bell Mobility etc.) Mobile subscriber identification number (MSIN; i.e., only one SIM can be used with the phone) Additionally, some phones, especially Nokia phones, are locked by group IDs (GIDs), restricting them to a single Mobile virtual network operator (MVNO) of a certain operator. Most mobile phones can be...
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