H3C XE 200 IP, Руководство по эксплуатации

Страница: 65 / 514

Operation Manual – Process Server Configuration
H3C XE 200/2000 IP PBX
Chapter 4 SIP Overview
4-3
4.1.2 Functionality and Features of SIP
SIP supports five facets of establishing and terminating multimedia communications:
z
Locating users or called SIP endpoints, the most powerful function of SIP. SIP has
registration function itself. In addition, it can enhance its user location service by
using the LS provided by domain name server (DNS) or lightweight directory
access protocol (LDAP).
z
Determining user availability, making sure whether a calling/called endpoint can
participate in a session. SIP supports multiple address description and addressing
styles, including username@hostname and called number@PSTN gateway
address and telephone number (such as Tel: 01012345678). Thus, a SIP caller
can identify whether a callee is attached to a PSTN network by callee's address,
and then initiate and set up the call to the callee through the gateway connected to
the PSTN.
z
Determining user capabilities, or the media and media parameters to be used by a
called endpoint. In a message exchange process, each SIP endpoint carries such
information in transmitted messages so that all other participants can learn about
its capabilities.
z
Setting up a session, or session parameters, at both callee and caller sides. Two
parties can select the appropriate capabilities for session setup through
negotiation about media and media parameters to be used.
z
Managing sessions by modifying session parameters or terminating sessions.
The following are the features delivered by SIP:
z
Open standards. It can accommodate new functions, products, and services
introduced by different service providers.
z
Flexible configurations. It accommodates a wide range of dialup, wire, and
wireless devices, allows highly flexible configurations, and can work with other
systems.
z
Scalable system. The system allows expansion as enterprises grow.
z
Support to remote users. With SIP, an enterprise network can extend to all its
users, wherever they are.
z
Competitive advantage potentials. More SIP-based services are emerging.
z
Consistent communication method. Management becomes easier as the result of
consistency in dialup mode and system access method used by branches,
SOHOs, and traveling personnel.
z
Quick launch. The system can be updated quickly to accommodate new branches
and personnel, as well as changes resulted from job rotation or relocation.
z
Easy to install and maintain. Even unprofessional individuals can install and
maintain SIP system configurations.