User`s manual

Chapter 7 Voice

This chapter first describes the SIP and Dial Plan configuration screens. The

last section (7.3 Telephone Calls) describes how to use the VoIP (Voice over IP)

and PSTN (Public Switched Telephone Network) voice services.

7.1 SIP

Session Initiation Protocol (SIP) is a signaling protocol for Internet conferencing,

telephony, presence, events notification and instant messaging. It is the Internet

Engineering Task Force's (IETF's) standard for multimedia conferencing over IP.

It is designed to address the functions of signaling and session management

within a packet telephony network. Signaling allows call information to be carried

across network boundaries. Session management provides the ability to control

the attributes of an end-to-end call.

Session Initiation Protocol is a peer-to-peer protocol.

There are four components in the SIP standard:

(a) User Agents (UA) - SIP phone clients (hardware or software)

(b) Proxy Server – relays data between UA and external servers

(d) Redirect Server – provides an address lookup service to UA