"Users will benefit because they will no longer require a proprietary unified messaging server that has limited interoperability with voice servers but can support a mixed telephony environment of both IP and [time-division multiplexing] systems," says Elizabeth Herrell, an analyst at Forrester Research, in a January report titled "Unified Messaging Is on the Rebound."

"Unified messaging is really an old architecture. It has been around since the mid-'90s. There is a shift happening, because Microsoft is getting into the business. Still, you can't really say that things will change overnight," adds Herrell.

Also changing the UM landscape -- though also not overnight -- is the introduction of stand-alone appliances that pull voice into a single stream of data on a message server, says Herrell, who cites systems from Adomo Inc. as an example.

Adomo offers voice messaging appliances that support 500, 1,000 or 2,000 users and can be stacked and clustered alongside private branch exchanges to convert voice streams into text-based Exchange data, according to company representative.

IT executives at SI International Inc., a large government contractor in Reston, Va., plan to use Adomo appliances to help outfit a new office campus in Colorado Springs, says CIO Steve Hunt. Specifically, the company will interface Adomo's voice-mail appliance with an existing PBX from Nortel and a local Microsoft Exchange server.