One of the two VoIP Gateway vendors I have had the pleasure of dealing with, AudioCodes has a nice write up about their product and Exchange 2007 UM.  Lior explains Microsoft's UM strategy and how to leverage AudioCodes' affordable devices in your UM deployment. 

Read Lior Moyal's entire article here

Overview

Today, a common setup is to have separate voice and email messaging systems. Emails are received by a server such as Exchange and are accessed through mail clients like Outlook. Voicemail systems are independent systems accessed via a telephone. Faxes are often received by stand alone machines and typically have to be manually sorted by a secretary or other personnel in order to be delivered to the correct end user. Both the users and administrators have to use  multiple sets of tools, one or more for each of these systems in order to manage their communication. This is a very inefficient setup.
Is it possible to do better than this?