ZyXEL Communications p-2612HNU-FX User Manual

Chapter 9 Voice

P-2612HNU-Fx User’s Guide

This section contains background material relevant to the VoIP screens.

VoIP is the sending of voice signals over Internet Protocol. This allows you to 
make phone calls and send faxes over the Internet at a fraction of the cost of 
using the traditional circuit-switched telephone network. You can also use servers 
to run telephone service applications like PBX services and voice mail. Internet 
Telephony Service Provider (ITSP) companies provide VoIP service. 

Circuit-switched telephone networks require 64 kilobits per second (Kbps) in each 
direction to handle a telephone call. VoIP can use advanced voice coding 
techniques with compression to reduce the required bandwidth. 

The Session Initiation Protocol (SIP) is an application-layer control (signaling) 
protocol that handles the setting up, altering and tearing down of voice and 
multimedia sessions over the Internet.

SIP signaling is separate from the media for which it handles sessions. The media 
that is exchanged during the session can use a different path from that of the 
signaling. SIP handles telephone calls and can interface with traditional circuit-
switched telephone networks.

A SIP account uses an identity (sometimes referred to as a SIP address). A 
complete SIP identity is called a SIP URI (Uniform Resource Identifier). A SIP 
account's URI identifies the SIP account in a way similar to the way an e-mail 
address identifies an e-mail account. The format of a SIP identity is SIP-
Number@SIP-Service-Domain.

Clear

Click this to erase all the speed-dial entries.

Cancel

Click this to set every field in this screen to its last-saved value.

Table 41   VoIP > Phone Book > Speed Dial