Communicator 2005 contact list may incorrectly list a contact as "Status unknown"

When you use Microsoft Office Communicator 2005 over a virtual private network (VPN) connection, your contact list may incorrectly list a contact as "Status unknown."

This problem occurs when the VPN connects to host server at a slow connection speed. When this occurs, Communicator 2005 cannot use Session Initiation Protocol (SIP) compression over the VPN connection.

This issue is fixed in the Communicator 2005 hotfix package that was released on October 19, 2006.

How to obtain the hotfix

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

To enable this hotfix package, follow these steps:

1. Exit Communicator 2005.
2. Click Start, click Run, type regedit, and then click OK.
3. Locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Communicator\SIPCompression
4. After you select the subkey in step 3, point to New on the Edit menu, and then click DWORD Value.
5. Type Mode, and then press ENTER.
6. Right-click Mode, and then click Modify.
7. In the Value data box, type 3, and then click OK.
8. On the File menu, click Exit to close Registry Editor.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.