Overview#Location Area Identity (LAI) internationally Unique Identifier is used for location updating of mobile subscribers.
Location Area Identity is composed of:
- Mobile Country Code (MCC)
- Mobile Network Code (MNC) - that identifies a Subscriber Module Public Land Mobile Network (PLMN) in that country, and a
- Location Area Code (LAC) - which is a 16 bit number with two special values, thereby allowing 65534 location areas within one GSM PLMN.
Location Area Identity is broadcast regularly through a Broadcast Control CHannel (BCCH). A Mobile Device stores it in the SIM Card. If the mobile station is moving and notices a change of LAI, it will issue a location update request, thereby informing the Home Location Register of its new LAI. This allows the provider to locate the Mobile Device in case of an incoming call.