asterisk users - Jan 2004 - rtp sound quality?

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?

Rich

-----Original Message-----
From: asterisk-users-admin@lists.digium.com
[mailto:asterisk-users-admin@lists.digium.com] On Behalf Of 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.

Where are you getting timing from? Zaptel device? Ztdummy?

-Josh

Rich Adamson wrote:
>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.

-- 
Bob Knight
[-w] the work option
bk@minusw.com
925-449-9163

Hi Rich!
> 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? 
First guess (rather likely): Silence supression

Second guess (unlikely): Non optimal "Voice frames per TX" as it is 
called in Grandstream setup; don't have a Mediatrix, so I can only guess. 
Should be 2 for the GS.

Cheers, Philipp

Chris Craft wrote:
>On Saturday 31 January 2004 21:31, you wrote:
><<<CHOP>>>
>  
>
>>I am just a low level c hack.  Before I go out and write any thing to do
>>this snmp admin stuff,
>>are there any linux tools I could use to do this?
>>    
>>
>
>
>Net-SNMP (http://freshmeat.net/projects/net-snmp/ , formerly UCB-SNMP or 
>something) is very handy for this.
>
Perfect. Thank you very much. bk.......

-- 
Bob Knight
[-w] the work option
bk@minusw.com
925-449-9163