The Gateway Mobile Location Centre contains functionality required to support LCS (LoCation Services). In one PLMN (Public Land Mobile Network

Public land mobile network

A public land mobile network is a regulatory term in telecommunications. A PLMN is a network that is established and operated by an administration or by a recognized operating agency for the specific purpose of providing land mobile telecommunications services to the public.A PLMN is identified...

), there may be more than one GMLC. The GMLC is the first node an external LCS client accesses in a GSM or UMTS network. The GMLC may request routing information

Routing

Routing is the process of selecting paths in a network along which to send network traffic. Routing is performed for many kinds of networks, including the telephone network , electronic data networks , and transportation networks...

 from the HLR (Home Location register

Network Switching Subsystem

Network switching subsystem is the component of a GSM system that carries out call switching and mobility management functions for mobile phones roaming on the network of base stations...

) or HSS (Home Subscriber Server

IP Multimedia Subsystem

The IP Multimedia Subsystem or IP Multimedia Core Network Subsystem is an architectural framework for delivering Internet Protocol multimedia services. It was originally designed by the wireless standards body 3rd Generation Partnership Project , as a part of the vision for evolving mobile...

). After performing registration authorization, it sends positioning requests to either the VMSC (Visited Mobile Switching Centre

MSC

- Computers:* Mario Strikers Charged* Microsoft Common Console Document, file for the Microsoft Management Console* Microelectronics Support Centre* Microsoft Corporation* MIDI Show Control* Message Sequence Chart...

), SGSN (Serving GPRS Support Node) or MSC (Mobile Switching Centre) Server and receives final location estimates from the corresponding entity.