GATEWAY MSC (GMSC)

GMSC FUNCTIONS

Gateway functionality enables an MSC to interrogate a HLR in order to route a mobile terminating call. It is not used in calls from MS’s to any terminal other than another MS. For example, if a person connected to the PSTN wants to make a call to a GSM mobile subscriber, then the PSTN exchange will access the GSM network by first connecting the call to a GMSC. The  MSC requests call routing information from the HLR that provides information about which MSC/VLR to route the call to. The same is true of a call from an MS to another MS.

GMSC IMPLEMENTATION

Any MSC in the mobile network can function as a gateway by integration of the appropriate software and definition of HLR interrogation information. In effect it then becomes a GMSC/VLR. In GSM systems, gateway functions are provided within the subsystem MSS. The only additional hardware required is hardware to interface to the signaling link to the HLR.

Gateway Function:

1. Find and interrogate HLR for roaming number.

2. Route the call according to the interrogation.