What to do when Media Server reports “Binding Failed”

If the Media Server needs to allocate a port for media transmission, and cannot bind, it will generate a log message such as:

MediaServerReporting:InitEndPoint [MS003003] C:179.1: RTCP socket binding failed with error code 10048

This is due to some other application already binding to some ports in the 7000-7499 range. This is typically due to the Microsoft DNS . To check which ports are bound at any point in time, you can run the following command from the DOS prompt:

netstat -ano -p UDP

Microsoft Windows allows you to define which port ranges will NOT be returned to any application/service that requests a random port number, via the following registry entry:


To ensure correct functionality, you should add the following ranges, without removing whatever the value already contains:

  • 5000-5100 – Management Console, FAX Server, SIP Port for 3CX PhoneSystem and Tunnel Ports, Other 3CX Components
  • 7000-7499 – 3CX Media Server (RTP) – LAN audio/video/t38 streams
  • 9000-9099 – 3CX Media Server (RTP) – WAN audio/video/t38 streams
  • 40000-41000 – Conference, IVR, Parking Orbits

Visit our Ports used by 3CX Phone System article for an always up to date list of ports used.

Screenshot for example purposes. Ports in the screenshot are not correct ports:

For more specific instructions regarding this registry entry, refer to: http://support.microsoft.com/kb/812873/

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