Home Location Register

 Home Location Register (HLR):

Home Location Register

The call roaming and call routing capabilities of GSM are handled by the Home Location Register (HLR).

It comprises all the administrative information of every subscriber that is registered in that corresponding GSM network. Also, the current location of the mobile station (MS) is available in the Home Location Register (HLR).

A unique International Mobile Subscriber Identify (IMSI) of each subscribe is maintained in the Home Location Register (HLR) database. Each home number can be identified by this number.

There is logically one Home Location Register (HLR) per GSM network, although it may be implemented as a distributed database.

The Home Location Register (HLR) database can be grouped into two types. 

1. Dynamic database: 

It contains the location information for each subscriber.

2. Permanent database:

It includes:

(i) International Mobile Subscriber Identity (IMSI) 

(ii) Service subscription information.

(iii) Supplementary services.

(iv) Service restriction.

(v) Mobile terminal characteristics.

(vi) Billing / accounting information.