In a Microsoft Exchange Server 2010 environment, when you log on to a Microsoft Office Communicator 2007 client, you may receive the following Exchange Connection error message:
Communicator could not retrieve calendar or Out of Office information from Exchange Web Services. Communicator will automatically continue to retry. If this problem persists, contact your system administrator.
In this situation, the Office Communicator 2007 client does not receive enhanced presence information from the Exchange Server 2010 server, such as Free\Busy information and Out of Office information.
This issue occurs because Exchange Server 2010 sends AutoDiscover and Exchange Web Services SOAP packets in code chunks. However, Office Communicator 2007 does not process SOAP messages in code chunks.
To resolve this problem, install the following update rollup:
2028885 Description of the cumulative update package for Office Communicator 2007: July 2010
Note After you install this rollup package, a SendMessageTimeout registry entry is automatically added into the registry under the following registry subkey:HKEY_CURRENT_USER\Software\Microsoft\UCCPlatform\Communicator
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.