Sip Ag Overview; Sip Ag Features Supported By The Ar1200 - Huawei AR1200 Series Configuration Manual - Voice

Huawei AR1200 Series Enterprise Routers
Configuration Guide - Voice

1.1 SIP AG Overview

This section describes the SIP AG in VoIP applications.
VoIP
On the Public Switched Telephone (PSTN), telephone lines are occupied exclusively. The fees
for toll calls are high.
To reduce data and voice fees and meet service requirements, voice over IP (VoIP) is used.
VoIP transmits voice services over the IP network. In VoIP, a voice gateway encapsulates voice
signals into frames and transmits them as IP packets. Currently, IP phone gateways implement
communication between the PSTN network and IP network. As PC-to-phone, phone-to-PC, and
phone-to-phone technologies have developed, the voice quality is improved greatly. VoIP can
meet commercial requirements.
Voice Gateway
The IP network is a packet switched network. The transmission costs on the IP network are lower
than those on the PSTN; therefore, VoIP will take place traditional voice phones gradually.
Replacing all phone networks with VoIP will take high costs. The step-by-step migration
solution is recommended.
In most enterprise voice solutions, phone networks of branches are reserved and the IP network
is used between branches.
In the step-by-step migration solution, a voice gateway is required to connect the two types of
networks. A router is often used as the voice gateway.
SIP
The Session Initiation Protocol (SIP) is a text-based signaling protocol. SIP messages are
classified into request and response messages. SIP can be used for creating, modifying, and
terminating two-party or multiparty sessions. SIP can be used for multimedia conferences,
remote education, and Internet calls.
SIPAG
A SIP access gateway (SIP AG) is a voice gateway that exchanges SIP signals with other devices
on the PSTN/ISDN and IP network. It can implement VoIP functions.

1.2 SIP AG Features Supported by the AR1200

This section describes SIP AG features supported by the AR1200.
Using a SIP AG as a Voice Gateway
As shown in
communication between the IP network and the PSTN or ISDN. The usage scenarios are as
follows:
Issue 03 (2011-09-30)
Figure 1-1, a SIP AG functions as an IP voice gateway to implement
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