Office Communicator 2005: data sharing on Windows Vista

Presence and chat worked in Office Communicator 2005 on Windows Vista, but desktop and file sharing failed with a firewall or Network Address Translator (NAT) warning.

I had been struggling with this for a while. Office Communicator 2007 does not support Office Live Communications 2005 server, so I have to keep using the 2005 client.

Cannot establish the data sharing session with user1, either because user1 canceled the session, or because you or the person you are calling is behind a firewall or Network Address Translator (NAT).

 

Installation order

Uninstall Microsoft Office Communicator 2005
Get the KB927853 hotfix from Microsoft. This update will install the NetMeeting 3.02 version which is compatible with Windows Vista.
Reboot the machine
Install Microsoft Office Communicator 2005

I had scripted Microsoft Office Communicator 2005 into an Altiris SVS application layer, but installing the hotfix did not resolve my problem. Make sure you uninstall Communicator first, or delete the SVS layer, and then reinstall the packages.