What is Unified Communications?
You've probably heard the term "Unified Communications" thrown around for awhile, so what is it? Good luck trying to find a clear definition from any one, Microsoft, Cisco, who ever...
Unified Communications (UC) is the concept that you can have access to all your communications from a single entity. (This is really my definition and the phrase "single entity" is used loosely)
Ok, then what is Unified Messaging (UM)? Depending on how you look at it Unified Messaging is really a subset of UC, as it only deals with messages (non-real time communications) such as email, fax, and voicemail. These concepts have just recently been embraced by Microsoft and you see these concepts in their new products, Office Communications Server 2007 and Exchange Server 2007. Exchange 2007 primarily deals with the UM portion of the UC concept, while OCS handles the real time communications (telephone, conferencing, instant messaging). So using my highly refined artistic abilities I drew a little picture of how I see UC and UM fits with Exchange and OCS.
(There are other products that fit in with in the UC concept, but I see Exchange and OCS as the main products.)
So where does Speech Server (2007) fit in?
Speech Server is really just a supportive product for UC, as you can use it outside the context of UC or UM, but if you wanted you could create a UM application using Speech Server as a front end of your mail server, such as Exchange 2007 (It doesn't have to be Exchange). You could also create an application which support RTC (Real Time Communications), an application such as a Follow Me, Find Me Application for telephony calls. (It seems this feature was taken out of the current OCS beta, but you could create your own.)