Microsoft released the Unified Messaging Web Service Sample.

Brief Description
The Unified Messaging Web Service Sample describes how to create proxy classes that interact with the Unified Messaging Web service. The proxy classes make it easier to implement the interaction between the client and the Web service.

System Requirements

• Supported Operating Systems: Windows 2000; Windows 2000 Advanced Server; Windows 2000 Professional Edition ; Windows 2000 Server; Windows 2000 Service Pack 2; Windows 2000 Service Pack 3; Windows 2000 Service Pack 4; Windows Server 2003; Windows Server 2003 Service Pack 1; Windows Server 2003, Datacenter Edition for 64-Bit Itanium-Based Systems; Windows Server 2003, Datacenter x64 Edition; Windows Server 2003, Enterprise Edition for Itanium-based Systems; Windows Server 2003, Enterprise x64 Edition; Windows Server 2003, Standard x64 Edition; Windows Vista

• Access to computers that are running Exchange Server 2007 that have the Client Access and Mailbox server roles installed.
• Wsdl.exe 2.0, which is included with either Microsoft Visual Studio 2005 or the Microsoft .NET Framework 2.0 Software Development Kit (SDK).
• Visual Studio 2005, to build the project that contains the Unified Messaging sample.