Presence and IntComm WG

[Jiri Kuthan <>]

a related link: Alcatel presentation in iptel workshop 2000,
see http://www.iptel.org/2000/presentations.zip, 56-slides. 
It shows how some codecs fit in the e-model, and how the
subjective quality relates to packet-loss, use of transcoders
and delay.

-jiri

At 06:08 PM 4/16/2004, Jeremy George wrote:

>  Not so good news and good news.  The not so good news is that I failed
>in coming up with a simple chart plotting mos v packet loss for gsm.
>
>  The good news is that I discovered that the ITU has created an 'e-model'
>(G.107 I think?) meant to replace mos scores on packet networks.
>Very basically, the e-model produces an r-value, the calculation of
>which appears complex to my three-semesters-of-calculus-decades-ago eyes.
>
>  Two interesting sources discussing the issues are:
>
>atr.alcatel.de/hefte/00i_1/gb/pdf_gb/06vleegb.pdf
>www.aptsec.org/seminar/meeting-2003/policy-forum/documents/INF05_Article-VOIP-QoS-Benchmarks-APT.doc
>
>  The broad relationship of r-value to mos score is:
>
>      r-value   mos
>      100-90     5     excellent
>       89-80     4     traditional toll quality
>       79-70     3     useable, some dissatisfaction expected
>       69-60     2     audible, poor
>       59-50     1     barely audible, very poor
>
>  GMS-FR (right?  there are actually three flavors of gsm) in ideal
>conditions gets an r-value of 74, equivalent to a 3.74 mos score.  What
>I couldn't find is how it performs in increasingly degraded circumstances.
>
>  For the SMM trial maybe the best thing is to leave the weather report
>as is?  But, I think exploring the e-model would be very useful for
>schools considering moving to VoIP in a big way.  Perhaps this would be
>something the VoIP ITEC might consider?
>
>- Jeremy
>
>-- 

--
Jiri Kuthan            http://iptel.org/~jiri/