H.323

ITU-T’s (International Telecommunications Union) standard – vendors need to comply to supply VoIP.
Encompasses point to point communications & multipoint conferences.
Consists of four components:

• Terminals
  • Endpoint host systems providing real time, two way comms.
  • Can communicate with another H.323 terminal, H.323 gateway or MCU.
• Gateways
  • Endpoint providing communication between terminal or another gateway.
  • Translates transmission formats e.g audio an dvideo codes.
  • Interface between network & Internet.
• Gatekeepers
  • Central point
  • Manages calls within it’s zone.
  • Translates alias address to transport address, grants/denies access based on call authorisation, source or destination address or other criteria.
  • Supports bandwidth and call management
• MCUs (Multipoint Control Units)
  • Provides capability for three or more terminals & gateways to participate in multipoint conference by multiplexing audio, video and data.