State of knowledge

October 2021

With estos ProCall Enterprise version, the operating mode of the RTPEndpoint and WebRTCndpoint side has been made configurable.


Operating mode for PBX streaming (RTPEndpoint) and client streaming (WebRTCEndpoint).

The operating mode for the PBX streaming side (RTPEndpoint) and for the client streaming side (WebRTCEndpoint) was previously fixed to Mode 4 (synced - synchronized sender and receiver clocks) in version 7, which can lead to increasing audio packet bursts in case of packet loss at the input of a media pipeline in specific customer environments.

In practice, this shows up in the form of increasing audio gaps as the call duration increases.


Change operating mode from synced to none – switch off buffering

As a workaround, the operating mode in the UC Media Server configuration can now be switched to Mode 0 (none – only use RTP timestamps) as of, if required. This disables the buffering of audio packets in the estos UC Media Server, prevents the increasing formation of audio packet bursts, and eliminates the frequent and increasingly long acoustic dropouts in the audio receive channel of the client.


Configuration file SdpEndpoint.conf.json

  • Using a suitable text editor such as Notepad++, open the estos UC Media Server configuration file SdpEndpoint.conf.json.
    This is located when using the standard installation paths under
    C:\Program Files\estos\UCServer\MediaService\emswindows\etc\kurento\modules\kurento\.
  • In this file, you will find the parameters jbufmodertp and jbufmodewebrtc.
    Both parameters are set to the value 4 by default. Change these two parameters to the value 0.

    Please be careful not to change the formatting and punctuation structure in the process.

    Save your changes and close the text editor.

Example configuration file

  • The content of the SdpEndpoint.conf.json, therefore, looks as follows, where the parameter localAddress will show the individual setting of an IPv4 address in the customer system:
   "audioCodecs" : [
         "name" : "opus/48000/2"
         "name" : "PCMA/8000"
         "name" : "PCMU/8000"
         "name" : "AMR/8000"
   "jbufmodertp" : 0,
   "jbufmodewebrtc" : 0,
   "localAddress" : "<YourIndividualIPv4Address>",
   "numAudioMedias" : 1,
   "numVideoMedias" : 0,
   "videoCodecs" : [
         "name" : "VP8/90000"

Save and restart

  • Make sure that no softphone calls are currently being made and take into account that no calls can be made within the following restart phase of the estos UC Media Server service either.
  • Restart the estos UC Media Server service via the Microsoft Windows Services Manager.

This completes the conversion of the estos UC Media Server jitterbuffer operating mode.

Restore default

Changing the jitter buffer operating mode from 0 to 4, i.e. from none to synced, in order to restore the operating default, is also possible in the corresponding way.

Behavior during updates or upgrades

Please note that according to the current state of development, the settings that deviate from the installation default are overwritten when an update or upgrade is installed, since the configuration file SdpEndpoint.conf.json is replaced in the process.

Therefore, check the settings after installing a server-side software change and perform the steps described here again if necessary.

Operating modes not supported

The operating modes available in addition

  • 1 - slave – slave receiver to sender clock
  • 2 - buffer – do low/high watermark buffering

are currently not supported in the estos UC Media Server. The activation of these operating modes is not supported by estos.