An update to Windows Messenger will allow users to place voice calls over the Internet from their PCs to regular telephones, opening a new partnering opportunity to companies that offer Voice-over-IP (VoIP) services and have equipment to support Session Initiation Protocol (SIP) signaling. The update is also necessary for new Windows XP computers to be able to use the instant messaging service in Exchange 2000.

VoIP Providers Can Participate

Microsoft's previous instant messaging client (MSN Messenger) already offers PC-to-phone capabilities from VoIP provider Net2Phone. However, because Windows Messenger uses a different protocol, SIP, for discovering users and establishing sessions, Net2Phone and other providers had to update their equipment to offer VoIP service to Windows Messenger users. This is a task that many VoIP providers were already undertaking: SIP is rapidly emerging as an industry standard, and the necessary hardware and software is available from Cisco, Nortel, 3Com, Indigo Software, and several other companies. (Microsoft plans to enter the market with a SIP proxy server called Real-Time Communication Server some time in 2002.)

Under Microsoft’s new Voice Services Program, any VoIP carrier that has implemented the following technical infrastructure can sign up to offer its services to Windows Messenger users:

• VoIP trunking, which allows voice data to be sent over IP networks.
• SIP-based proxy servers and soft switches, which route SIP-based calls to and from multiple users. (Without this infrastructure in place, two SIP users must know each other's IP address.)
• SIP-VoIP-to-PSTN (Public Telephone Switched Network) gateways, which allow SIP-based voice calls to connect to the regular phone system.

In addition, participating carriers must meet certain interface criteria: for example, they must make a Web site available with a complete breakdown of customers' monthly billing information.

By participating in the Voice Services Program, carriers gain potential access to tens of millions of Windows XP customers, all of whom will receive Windows Messenger with the operating system. The first time users want to place a PC-to-voice call, they will be presented with a list of all the carriers who offer service in their area. So far, five companies have signed up to offer VoIP services to Windows Messenger users, beginning on the official Windows XP retail launch date of Oct. 25: Net2Phone, Deltathree, Dialpad Communications, Callserve (which is based in Europe), and Telus (Canada's second-largest telecommunications provider). Rates are comparable to or slightly cheaper than regular long-distance, ranging anywhere from US$.02 per minute for domestic calls to US$.99 per minute for international calls to some countries.

Download Required

To use these services, users of the Windows Messenger client that ships with the initial release of Windows XP will have to download a 1MB update from Microsoft. Even with the update, users behind network address translation (NAT) devices, which are used by many businesses and ISPs to share a single IP address among multiple computers, will not be able to place voice calls at this time. The update will also add a window to the Messenger client that tracks usage (for example, a user's monthly bill, or how much time is left on a prepaid service). The update is also required for some Windows XP users to use Windows Messenger with Exchange 2000 instant messaging. (See "Update Required for Exchange IM on XP".)

Beginning Oct. 25 (to coincide with the retail launch of Windows XP), the update will be offered automatically to all Messenger users when they connect to the public MSN Messenger system and will show up on Windows Update.

Users should note that even if they download the update, their Windows Messenger client will not be able to interact with certain MSN services, such as MSN Chat, and will not be able to send text messages to MSN Mobile users, as the MSN Messenger client can do. Microsoft is working on upgrading Windows Messenger in the future so it offers all the functionality of MSN Messenger, but has not announced a date for the upgrade.

Older Clients Can Upgrade

Users can apply a different patch to the older MSN Messenger client to obtain a choice of all the PC-to-phone providers participating in the Voice Services Program, rather than having to use the default service provided by Net2Phone. In addition, the update is necessary for placing PC-to-PC voice calls with Windows Messenger users; otherwise, the two clients can only exchange text messages.

The update for MSN Messenger, while allowing it to interact with SIP-based systems, does not convert it into a full SIP client, so Messenger users will not get other benefits offered by Windows Messenger, such as the ability to participate in one-to-one videoconferencing and share applications and whiteboards.

Resources

Basic information about the Voice Services Program is available at www.microsoft.com/serviceproviders/voiceservices/. This page also contains a link to a registration form, which companies can fill out to receive further information.

The update will be available beginning Oct. 25 from windowsupdate.microsoft.com and www.microsoft.com/exchange/downloads/2000/.

For an overview of SIP, and notes on where to find more information, see "Session Initiation Protocol" on page 10 of the Aug. 2001 Update.

For background on Windows Messenger, see "Windows Messenger Moves IM, Conferencing in New Direction" on page 8 of the Aug. 2001 Update.