Greetings,
Here's a short follow-up to yesterday's presentation of Zebbra guys.
What Markus and Roland have presented, is an approach to monitoring
the quality inside the box (CUCM in their case). But there are
actually ways to monitor the quality outside of the box, and they have
been around for a while.
For example, I've seen a demonstration of Malden MultiDSLA tool over
10 years ago. At that time they only had the analog interface that
emulated a handset, and two Malden boxes were sending an audio sample
to each other and assessing the quality of received audio. The tool is
quite expensive though.
There are currently several commercial solutions for audio quality analysis:
POLQA (expensive), recommended by ITU-T: it compares two audio files
and produces the quality assessment score.
Sevana AQuA (less expensive): it also compares two audio files and
produces several quality metrics. I compared it with PESQ (predecessor
of POLQA), and AQuA works significantly faster. It was very helpful in
detecting lost RTP packets in the tests where I could not place a
packet sniffer wherever I wanted.
There are also various approaches to passive quality analysis, and
some are documented in ITU-T P.563 and G.107. Sevana is also offering
its PVQA tool that tries to detect packet loss and audio distortions
by analyzing the input audio.
I could not find any open-source tools which would help in quality
analysis at the audio level. But there's plain old tshark which
produces the loss and jitter statistics for RTP streams, and it's
pretty efficient if you are able to capture the traffic at the
receiving end. Also VoIP monitor provides the ability of G.107
analysis on captured data packets.
Here's my detailed article on using Sevana AQuA:
https://txlab.wordpress.com/2015/06/02/quality-assurance-for-voip-calls-2/
And here's my demo lab, and you have a possibility to send an audio
recording for Sevana PVQA analysis:
http://voxserv.ch/demolab.html
cheers,
--
Stanislav Sinyagin
Senior Consultant, CCIE #5478
ssinyagin@k-open.com
+41 79 407 0224