• United States
by Christine Perey

Working with Windows Messenger and SIP

Nov 04, 20024 mins

The first thing the IT manager must have in order to prepare a network for next generation Windows Messenger-mediated applications is a clear definition of what is needed from an application user point of view. Suppose you are a company that has Windows XP and Windows Messenger installed on a significant proportion of desktops.

If users want you to support the ability to have an IM session begin with chat between two people in your enterprise and escalate to a multimedia session (voice and video over IP), then you will need to ensure several things:

Note that the following does not support a multipoint conference. To support more than two users in a session, you will also need a multipoint conferencing server such as the FVC Conference Server with a SIP proxy, VCON’s MXM 3.0 (SIP proxy included) and VCON Conference Bridge, a RADVISION viaIP conference bridge combined with a third party SIP proxy or a SIP-based media mixing device (there are a few out as part of an IP-PBX).

What you MUST have Who provides it Benefits
IM client that supports SIP (ie. Windows Messenger) or IM client and a SIP gateway (the Lotus SameTime strategy) In the case of XP, built into the OS. In the future, if a third party offers an IM client with built-in SIP support, it will be an application that the user or IT manager must install Provides presence, supports chat and upon request, the client SIP signaling establishes connection and exchanges information with the IM server
Windows XP operating system Microsoft, under license Built in support for SIP
IM server in the case of Windows Messenger, Microsoft MSN Messenger service is free. Offers presence for users to see who is on-line and at their desk
Universal Plug and Play support in NAT devices and routers Manufacturers have released Permits the passage of media streams
Headset or microphone and speakers User or enterprise Microphone captures the voice and speakers produce the voice of the other person
Camera (for video) User Capture of local content, if both users want to see one another. Without a camera, the user can accept a video request and the call will be established without video source.
Low latency network connectivity (about 64k for voice only, about 100kbps to 200kbps uninterrupted for video) Enterprise A conditioned (low latency, low congestion) network connection permits the media to travel without interruption, pops or artifacts

If you want to support the ability to have an IM session begin with chat between two people in different enterprises connected over the Internet and escalate to voice and video over IP, then the equation is relatively complicated. The fastest solution is to place an enterprise user into a DMZ or provide a fixed IP address outside the firewall. Alternatives may be supported through an Internet-based server-initiated conference.

However, if you want to support the ability to have an IM session begin with chat between people in different enterprises and to have that escalate to a PSTN call, then you will need:

In addition to the above, you MUST have the following do this between enterprises

Who provides it Benefits
A SIP application server or an IP PBX with built in SIP support (the PBX would be a specific type of application server) eDial, Sphere Communications, Nortel Networks, Mitel, others The request for a SIP-based meeting will transmit the client system’s request to a PSTN/voIP gateway
voIP/PSTN gateway Cisco, Nortel Networks, AudioCodes, RADVISION, many others Performs protocol translation and resolves the phone number of the called party over the circuit switched network, provided that the number of the PSTN connected IM session participant is registered with the application server or a gatekeeper

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