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DRAFT

 

This module has been updated to provide additional quality statistics in the form of an Asterisk Media Experience Score. The score is avilable using the same mechanisms you'd use to retrieve jitter, loss, and rtt statistics. For more information about the score and how to retrieve it, see https://wiki.asterisk.org/wiki/display/AST/Media+Experience+Score

The MES is calculated from:

  • Average RTT
  • Average Jitter
  • Jitter Standard Deviation
  • Packets lost

The formula used is loosly derived from the Mean Option Score (MOS) as described in ITU-T G.107 and ITU-T P.800.1. To avoid direct comparisons to MOS however, the MES is reported as a value between 0 and 100. Since the highest MOS to be expected on a VoIP call is 4.5, the highest MES reported will be <= 90 (usually around 85).

The MES can be retrieved from the Dialpln using the same mechanisms available to retrieve the other rtp/rtcp stats:

  • ${CHANNEL(rtcp,<stat>)} (chan_pjsip only) using the stats:
    • all_mes
    • txmes
    • rxmes
    • remote_maxmes
    • remote_minmes
    • remote_normdevmes
    • remote_stdevmes
    • local_maxmes
    • local_minmes
    • local_normdevmes
    • local_stdevmes

  • Channel Variables:
    • RTPAUDIOQOSMES
    • RTPAUDIOQOSMESBRIDGED
  • AMI Events:
    • RTCPSent
    • RTCPReceived

 

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