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Troubleshooting IP telephony

Updated: January 21, 2005

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2, Windows Server 2008, Windows Server 2008 R2, Windows Server 8 Beta

Troubleshooting IP telephony

What problem are you having?

A program fails to get a multicast address from the MADCAP server.

Cause:  The server is not reachable from the client, or the server is not set up correctly.

Solution: The MADCAP server and client must both be in the same domain. The MADCAP server must be configured correctly.

See also:  Using multicast scopes; Enabling IP multicast; Checklist: Installing IP multicast video conferencing; Create a multicast Telephony scope.

Programs warn that they are using a local random address allocation when users create conferences.

Cause:  All addresses have been allocated for the scopes assigned for MADCAP.

Solution: Expand the size of the MADCAP scope.

See also:  Using multicast scopes; Enabling IP multicast; Checklist: Installing IP multicast video conferencing; Create a multicast Telephony scope.

A client cannot see all participants in a multicast conference.

Cause:  Servers running Routing and Remote Access may not be configured correctly for multicast telephony.

Solution: Check that multicast is enabled in both directions on servers running Routing and Remote Access.

See also:  Understanding Multicasting; Configure IP Multicast Support; Using the IP multicasting utilities.

Audio or video does not function correctly in a call or conference.

Cause:  Either the audio or video is working incorrectly, or the system is using an older audio or video driver that is incompatible with Windows Server 2003 operating systems. Test audio and video on your computer by doing the following:

  • Install and use Sound Recorder to check your microphone and speakers. Sound Recorder is an audio program that is available on an optional basis.

  • Use a video capture program to check the video camera and its settings, such as Vidcap32, found in the Platform Software Development Kit (SDK).

Solution:  Check the audio or video equipment manufacturer's Web site for the latest Windows Server 2003 family-compatible drivers.

There are audio or video device errors during calls or conferences.

Cause: The audio or video device is being used by another program, or the sound card does not support full-duplex functionality.

Solution:  If closing another program that is using an audio or video device does not resolve the problem, then check that the sound card and driver support full-duplex functionality:

  • Install and start Sound Recorder, and record a long message (about one minute). (Sound Recorder is an audio program that is available on an optional basis.) Rewind the recording, and start Sound Recorder again, so that it appears in two places on the desktop. In the first instance of Sound Recorder, start playing back the recording you made, and then use the other instance to simultaneously record another message. If you can record and play back simultaneously, then your system supports full-duplex audio.

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