Issue TOC Print full article Print this page Download as PDF E-Mail this URL Discuss this article Flame the author     In this article Introduction RFP Deliverables Interactive Intelligence Communité version 2.2 Cisco Systems Unity 4 THe Benefits of SIP Complete Responses to RFI If Not Sans SIP, Avaya Coulda Been a Contender IP PBXs Going Strong Hey Buddy, Got Speech? Report Card

Why focus on unified-messaging vendors that support the Session Initiation Protocol? SIP is a call-processing protocol designed to set up, modify and tear down sessions. Sessions can be point-to-point telephone calls or multimedia conferences. SIP is not dependent on a single conference-control protocol, like H.323 is, and does not dictate a method to transport the session traffic. It can operate over TCP or UDP, where multiple SIP transactions can be carried out in a single TCP connection or UDP datagram.

But it's more than just an efficient signaling protocol. SIP can boost support for mobile professionals. If a remote user registers his or her location with a SIP server, a UM application can direct SIP messages to the user's location, be it a remote office or a cell phone.

It is also a compelling protocol for enterprise networks. SIP can operate as a stateful or a stateless protocol. As a stateless implementation, it can scale to large networks where servers do not have to maintain state information on calls once a session is initiated. It integrates well into enterprises that leverage Web-browser interfaces because it uses HTTP formats to describe messages. And the message description is not limited to HTTP but can be transmitted in a number of ways. For example, it could be described in MIME or XML. Because it is based in HTTP, SIP can also support Java and JPEG and provide a rich multimedia experience.

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Both Cisco's Unity and Interactive Intelligence's Communité support SIP, and most other vendors we talked to said they'd add SIP support to their products this year. This will let these products work with any SIP-enabled PBX, such as Zultys' MX1200. Without a new SIP PBX, these UM products require a SIP-enabled proxy server and a gateway to the PSTN to enable SIP phones on the desktop (see diagram, below). Communité can work with its Interactive Center Platform as the SIP gateway. The Interactive Center can also support Communité on the same platform but it is not as feature-rich as the stand-alone version. Cisco would leverage its AS5300 Access Server or a 2600 or 3600 series router as the SIP gateway. Either of these solutions can integrate an IP PBX, though Cisco is limited to Call Manager.

SIP provides more options for telephone sets as well. Rather than taking the default phone set supplied by a vendor, any SIP-supported phone will do. In addition, enterprises can upgrade their workstations to Microsoft Windows XP. Its native support for SIP enables a fully functional softphone through Messenger--something to think about if considering Unity, which does not include a softphone. Communité provides its own SIP softphone with the Interaction Client.