This paper offers a description of Gatekeeper CX6800-Gatekeeper, an IP infr
astructure server for realizing VoIP (Voice over IF) which is a voice servi
ce on IP network. In addition to call control function based on H.323 proto
col, this paper explains its supplementary services as well as high availab
ility and operation/maintenance functions that have been deployed for large
-scale networks.