Terminology

A multimedia communication protocol that sends or receives files via one-to-one communication over a LAN or the Internet.

A communication control protocol for Internet telephone that utilizes VoIP (which converts voice information to IP packets) and is equipped with functions such as creating, modifying, and terminating sessions with one or more participants.

A gatekeeper manages devices connected to an IP network and converts alias telephone numbers to IP addresses and performs authentication functions. In addition, a gatekeeper governs band (transmission rate assignment) and access control.

A SIP server mediates connection requests between devices connected to an IP network and is composed mainly of servers that have the following three functions:

• Proxy server: Receives SIP requests and forwards them on behalf of the requestor.

• Registrar server: Receives information about a device's address within an IP network and registers them in the database.

• Redirect server: Used to inquire the destination address.

A gateway connecting a telephone network and IP network, it has functions such as protocol conversion for connecting these different networks, and also connects communication devices (telephones, facsimiles, etc.) to a LAN or other network.