gatekeeper (GK)
A gatekeeper (GK) is a central control element in H.323 networks for routing signaling information, for address translation of telephone numbers and IP addresses, and for their conversion, respectively.
In addition, the gatekeeper records charges and allocates them to partners in the networks and services, and provides bandwidth management in the context of quality of service( QoS).
When using a gatekeeper for call control, registration by means of a gatekeeper request( GRQ) is required on the terminal side, which the gatekeeper confirms with a gatekeeper confirm (GCF) or rejects with a gatekeeper reject (GRJ). To register the terminals with the gatekeeper, they use the RAS protocol, which is handled via Q.931 or H.245. As an independent logical unit, a gatekeeper can be located within a terminal or gateway.