After you configure fixed port assignments for the Session Initiation Protocol (SIP) Communications Service in Microsoft Windows Messenger 5.0, you may experience one or more of the following symptoms:

• The SIP Communications Service does not initialize correctly, and the SIP Communications Service Account option no longer appears on the Accounts tab of the Windows Messenger Options dialog box.
• If Windows Messenger is configured to sign in to the .NET Messenger Service and to sign in to the SIP Communications Service account, you can still sign in to the .NET Messenger Service successfully.
• You cannot accept incoming invitations for audio sessions, for video sessions, for application sharing sessions, for whiteboard sessions, or for remote assistance sessions. In this scenario, the session does not connect successfully, or you receive an error message that is similar to the following:
  Cannot launch the Tuning Wizard at this time.

This issue occurs if you have incorrectly configured the fixed port assignments for Windows Messenger. This issue may be caused by conflicting port assignments.

To resolve this issue, verify that the fixed port assignments that you use for Windows Messenger do not conflict with other port assignments. Additionally, make sure that you configure a range of ports that is sufficient to handle SIP signaling, media traffic, and Microsoft Exchange Server server-to-client traffic.

SIP values and media port values that are incorrect include one or more of the following:

• Port assignments that overlap other ports that are used by other programs or services.
• Port numbers that are lower than 1,024.
• Port numbers that are higher than 65,536.

If you specify an incorrect port assignment in the Exchange Connection Configuration dialog box during the configuration of an Exchange Instant Messaging account in Windows Messenger, you receive a message that is similar to the following when you try to sign in: However, if you specify a port assignment that is not valid for the SIP Communications Service, you are not notified and you may experience the behaviors that are described in the "Symptoms" section of this article.

Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To configure fixed ports for the SIP Communications Service on a computer where Windows Messenger 5.0 is installed, follow these steps:

1. Click Start, click Run, type regedit in the Open box, and then click OK.
2. Locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\RTC\PortRange
3. In the right pane, right-click Enabled, and then click Modify.
4. In the Value data box, type 1, and then click OK.
5. In the
   PortRange
   registry key, create the following registry values, where portnumber is the port number that you want to assign:
   Value name:

   MinSIPDynamicPort

   
   Value type: REG_DWORD
   Value data: portnumber (decimal)
   
   Value name:

   MaxSIPDynamicPort

   
   Value type: REG_DWORD
   Value data: portnumber (decimal)
   
   Value name:

   MinMediaPort

   
   Value type: REG_DWORD
   Value data: portnumber (decimal)
   
   Value name:

   MaxMediaPort

   
   Value type: REG_DWORD
   Value data: portnumber (decimal)
6. Quit Registry Editor, and then restart the computer.