[Asterisk-Users] Dead air on 7960 sip at start of call.

[Chris Glover]

Hi,

I've noticed the same thing with my 7960 running SIP 7.1. I came to the
conclusion that the Cisco does some clever echo cancellation, and that
pause is the echo canceller training. I don't think it's an Asterisk
problem. My Grandstream 101 works perfectly.

Chris

-- 
Chris
----------------------------------
E Mail:	chris at glovercc.clara.co.uk
SIP: 84411389 at voiptalk.org
IAXTEL: 17003366726

On Thu, 24 Jun 2004, Sam Tilders wrote:

> Hi,
>
> Despite much searching, I can't find anything quite like the problem
> we seem to be experiencing with our recently activated asterisk pbx.
>
> Of four people answering several calls per five minutes, I
> have reports of the occasional call starting with dead air.
>
> The user picks up the call from the queue, and they can hear that the line
> is too quiet. If they start talking, the caller either doesn't
> hear them, or only hears the end of the first sentence.
>
> Reports are that this silence at the start of the call lasts
> from 4-5 seconds, sometimes over 10 seconds and more rarely over
> 20 seconds.
>
> After the period of silence the call proceeds with no further problems.
>
> I have taken packet dumps of extended periods, there is nothing consistently
> different about the calls with silent start compared to those without the
> problem. The SIP INVITE is sent to the phone, the phone rings, and OK's the
> call. The RTP stream begins straight away.
>
> I'm using cvs-head as of 2004-06-10, CVS-D2004.06.09.14.00.00, recently
> updated from v1-0_stable dated a few weeks before. This problem
> existed with both versions.
>
> The phones are Cisco 7960's with SIP image 6.3, the calls are incoming
> on an E1 connected to a TE410P. Calls are queued and the phones
> statically defined as agents in the queue which has a ringall
> strategy. There is no queue announcement played to the answering user.
>
> Asterisk in vvv verbose doesn't log anything different when this occurs.
>
> So, has anyone else heard of something like this? Or have a suggestion
> for further investigation?
>
> Cheers.
>