Known issues with PIC (Public IM Connectivity)

This article describes the known issues that occur when public instant messaging (IM) connectivity is configured with one of the three available public IM service providers after you install Microsoft Office Live Communications Server Service Pack 1 (SP1) or Microsoft Office Communicator 2007. This article also lists the known IP addresses that are used by each public IM service provider.

http://support.microsoft.com/kb/897567