[Asterisk-Users] rtp sound quality?

[Rich Adamson]

> >pstn -> sip gw -> * -> C7960
> >
> >When I dial into * via the pstn, I hear the ivr menu just fine (good
> >quality). I press 3000 (valid extn), and I begin to hear ringing however the 
> >ring back is very very choppy.
> >
> >I answer the C7960, and speech is clear in both directions. Place the C7960
> >extn on hold, and the MOH is very choppy. Checking 'sip show channels' indicates
> >both the sip gw and C7960 are using ulaw; Both are 100 meg on local LAN. Top
> >suggests all processes running less then 1 or 2 percent.
> >
> >The choppy sound only happens on the sip gw (Mediatrix 1204). MOH between two
> >C7960's works fine. MOH via x100p works fine.
> >
> >Tried canreinvite=no and yes; no difference. Using a packet sniffer, I see a
> >~200 millisecond delay about every 1/2 second or so (varys), but nothing within 
> >the trace to hint at a layer-2 problem.
> >
> >Anyone have any thoughts as to why ringback and MOH are choppy but conversations
> >are fine?  Anything else I can look at to isolate the issue?
> >
> You need to disable VAD on the 1204.
> The 1204 stops xmiting RTP to * if it does not detect any acoustic energy.
> 
> * can not clock itself sending RTP packets.
> It relyes on receiving RTP packets for it's timing.
> Try singing along with your MOH and the choppiness should go away, or
> disable VAD, or fix * RTP driver.

Thanks Bob, that fixed it. Any other hints/issues/default values that I should
muck with, or is that about it?

Seems like it works pretty good; excellent echo cancellation, etc.

I haven't done anything with the box as yet for dialing outbound. Anything
to be concerned with, special parameters, etc?

Rich