Editing Network switching subsystem (section)

===Procedures implemented===
The main function of the HLR is to manage the fact that SIMs and phones move around a lot. The following procedures are implemented to deal with this:
* Manage the mobility of subscribers by means of updating their position in administrative areas called 'location areas', which are identified with a LAC. The action of a user of moving from one LA to another is followed by the HLR with a Location area update procedure.
* Send the subscriber data to a VLR or SGSN when a subscriber first roams there.
* Broker between the G-MSC or SMSC and the subscriber's current VLR in order to allow [[GSM services#Call set up process for incoming calls|incoming calls or text messages to be delivered]]{{Broken anchor|date=2024-07-22|bot=User:Cewbot/log/20201008/configuration|target_link=GSM services#Call set up process for incoming calls|reason= The anchor (Call set up process for incoming calls) [[Special:Diff/8922898|has been deleted]].}}.
* Remove subscriber data from the previous VLR when a subscriber has roamed away from it.
* Responsible for all SRI related queries (i.e. for invoke SRI, HLR should give sack SRI or SRI reply).