HLR

 Permanent database about mobile subscribers in a large service area (generally one per GSM Network operator)

 Database contains subscriber & location information.

 Database contains IMSI (International Mobile Subscriber Identity), prepaid/postpaid, roaming restrictions, supplementary services.

 Each Subscriber is assigned IMSI to identify home user

OMC

 To maintain all telecommunications hardware & Network operations with a particular market.

 Manage all charging and billing procedures.

 Manage all mobile equipment in the system.

 The OMC also has provision for adjusting all base station parameter and billing procedure as well as providing system operators with the ability to determine the performance and integrity of all equipment‟s in the system.