User's Manual

6 Overview

Nortel Networks Confidential

• Redirect Server

The SIP Application Module decides whether to proxy or redirect the

call separately for each individual request. This decision is made

based on subscriber service logic. If the decision is to redirect the

request, a 302 Response message is returned with a list of alternate

locations.

• Registration Server

The Registration Server performs registration on messages it

receives from clients. The Registration Server stores information in

the database.

• Location Server

The Location Server performs location lookup services using

domain and user information stored in the database.

The SIP Application Module integrates the above logical servers,

which are all defined in SIP Draft RFC 2543 (see note for specific

reference), into a single server with the enhanced services provided

by the Back-to-Back User Agent.

Note: J. Rosenberg et al, SIP: Session Initiation Protocol,

Internet Draft draft-ietf-sip-rfc2543-bis09.txt, IETF, Feb 27, 2002.

Network configuration

The SIP Application Module is configured with two network cards to

allow for a network configuration that has a private side and a public

side. Figure 2, “Example of network configuration,” shows the

SIP Application Module and RTP Media Portal with public ports and

ports that are internal to the private network. This network configuration

provides security by placing all the components in a private network

and exposing only the public signaling and ports to the public network.