[Asterisk-Users] How to learn or teach VoIP QoE

[Steve Underwood]

Mojo with Horan & Company, LLC wrote:

> I've heard a MOS of 4.4 is ulaw/alaw, presumably like a local exchange 
> call through the pstn.
>
> testyourvoip.com tells me that the highest score available with G.729 
> is 4.2, which is pretty darn close to 4.4.

Alaw and ulaw are about 4.4. ulaw on a robbed bit trunk is about 4.3. 
G.729 is about 3.9. That doesn't sound like a big spread, but MOS tends 
to bunch them together. G.729 at 3.9 is pretty reasonable, while 
anything scoring 3.0 is bloody awful.

>
> I don't know why I think this (or why I've heard it (or if it's 
> right)) but I think gsm is 3.8?  Maybe someone can confirm or 
> disconfirm this. This kinda seems like the codec my long distance 
> calls go out on but I'm not really sure.

3.8 sounds about right.

>
> http://www.testyourvoip.com/results.html?id=071GM0&result=0
> (one of my more POOR results) approximates about 2.75 for 'tin cans 
> and string', 3.2 for a crummy cell phone call, about 3.9 for a decent 
> cell call, 4.4 or so for 'like calling next door', and the mystical 
> 5.0 for 'better than being there'.
>
> I wonder if 16kHz wideband codecs would bring our voice-carrying 
> experiences into the 5.0 range?

Much of the reason ulaw/alaw is way below 5.0 is due to bandwidth 
limitations. 16kHz sampling gets much closer to 5.0 It takes more like 
32kHz sampling to actually reach 5.0, though.

Steve