Microsoft will unveil its plans to merge telephone and computer systems under the "unified communications" banner, in San Francisco later today.

The software giant is launching Communications Server, an extension to Exchange, which will connect Exchange server email to office telephone systems.

The upshot? Users will be able to check their voicemails as text in their email inboxes, and have emails read to them by phone. Users can also leave voice messages with the Exchange server itself, to alert colleagues to changes to a scheduled meeting, for example.

But Microsoft doesn't have this space all to itself. There are plenty of open source products available that do similar things with big chunks of market share already tied up. IBM is also set to launch its offering, Lotus Sametime, later in the summer. ®