Apart from supporting basic IP services, Selsius also does a good job of managing bandwidth usage, incorporating noise-suppression technology in its phones and gateways. While this keeps background noise from generating unnecessary traffic, the feature can also work against you. Some people speak too softly, and their low decibel levels result in parts of the conversation being lost as the noise suppression kicks in. Having to ask the other party to speak up gets annoying quickly, though to be fair, this only happens on rare occasions. In addition, the Selsius gear doesn't generate background "comfort sounds," so whenever the noise suppression kicks in there is a dead silence that we found somewhat awkward.

Selsius is also on top of codec support, with strong G.711 and G.723 implementations. Most noticeably absent is support for G.729, a low-bandwidth codec favored by many of the other H.323 gateways on the market. This is perhaps the biggest hurdle for integrating the Selsius gear into a mixed-vendor environment, though this shortcoming should be addressed by the end of this year, according to the vendor. Selsius' frame-generation rate was also pretty good, with utilization ranging between 20 and 130 packets per second, depending on the speaker's volume and steadiness, and other environmental factors.

Overall, this is a technically sound solution, though it could stand some minor improvements. It is not ready for enterprisewide deployment, but it is certainly suitable for trial usage in small or medium installations. In particular, users of modern PBX equipment will not be impressed with the Selsius solution's feature set, which is very much a work in progress. Nor do we believe that most of the data networks in use in large corporations can handle the traffic of widespread VoIP deployment. But small-to-medium-sized companies that do not face these issues can deploy it comfortably, as can organizations with small branch offices or isolated networks.

The CallManager The heart of the Selsius IP-PBX suite is the NT-based CallManager software. In particular, the CallManager acts as the central management console for Selsius devices, and is used for configuring a phone's extension numbers and function buttons, routing plans for the gateways and other system features. It also provides call-management services for all Selsius devices on the network, and lets you integrate H.323 products into the virtual PBX setup.

The CallManager's interface is a collection of Active Server Pages (ASP) running on Microsoft's Internet Information Server (IIS), with management tasks handled through a Web browser on the user side, and configuration data stored in a Microsoft Access file on the server's drive. Overall, the configuration process is fairly straightforward and easy-to-understand, though we did encounter various ASP script errors on a server that had many other services running on it.

In our case, we found that the tight integration with IIS was a problem, since we could not run the software on the system of our choice (due to the ASP errors), and were unable to use another Web server (such as Netscape's FastTrack) for the configuration services. Indeed, almost all of Selsius' advanced features are tightly linked to a Microsoft service in one form or another. Even the free voicemail server that comes with the CallManager uses MAPI profiles on the host NT Server to route voicemail messages to different e-mail accounts (rather than just using SMTP).

Once these issues were resolved, we found the configuration services quite clear and easy to use. We were able to define extension numbers for each of the Selsius Ethernet phones, as well as for the various H.323 software in use on our network. We were also able to design call-routing plans easily, incorporating wild cards and dialing-string management strategies. Using this setup, all of our local devices were assigned four-digit extensions, while the dialing pattern of "9@" was established as a routing plan for the analog gateway. Users could dial any four-digit extension, or could place outbound calls simply by dialing "9" and any telephone number.