[asterisk-users] Terrible clicking on T1

[Gleim, Jason]

> On Thu, Aug 09, 2007 at 11:39:38AM -0400, Gleim, Jason wrote:
> > I have an Asterisk box connected to a Nortel Option 11C via a T1. In
the
> > Asterisk box we have a Sangoma A101C and in the Nortel we have a
TMDI
> > card. The Nortel is also hooked to the PSTN via a T1 on a different
> > NTAK09 PRI card. I've included the Zapata.conf and zaptel.conf files
> > below.
> > 
> > Our issue is that when a call is sent over the tie line between the
two
> > systems, the audio on the Asterisk side is terrible. There are rapid
> > 'clicks' on it similar to when you have a cell phone close to an
analog
> > phone or a set of computer speakers. The clicks start as soon as the
> > audio channel is opened (when I start to get rings) and it only
affects
> > the Asterisk side of the call. But, it affects both inbound and
outbound
> > audio on that side. On the Nortel side, the audio they hear is soft
and
> > distorted. On the Asterisk side, the audio they hear is full of the
> > clicking but broken thru when the caller speaks. It's almost like
the
> > 'silence packets' are being interpreted wrong by Asterisk. If I put
the
> > Asterisk box on the T1 for the PSTN, it works perfect.
> > 
> > The best part of all this... if we disable the TMDI card in the
Nortel
> > and then re-enable it, the audio is pristine... until the Nortel
runs
> > it's nightly maintenance routines. Then the noise is back the next
day.
> > We can always clear the problem with the disable/re-enable trick but
it
> > always come back after maintenance.
> 
> My bet is clock-slip due to a fight over who's clocking the line.
> 
> Cheers,
> -- jra
> -- 
> Jay R. Ashworth                   Baylink
jra at baylink.com
> Designer                     The Things I Think
RFC 2100
> Ashworth & Associates     http://baylink.pitas.com
'87 e24
> St Petersburg FL USA      http://photo.imageinc.us             +1 727
647 1274

I thought that might be an issue too... and it was originally. When we
started out, I had the Sangoma card generating the timing for the span
but we could never get the d-channel to come up. Turns out that since we
were connected to the PSTN, we had to let the Nortel set the timing on
the span because it was receiving the timing from the CO. (Essentially
the timing needed to 'flow' away from the CO)

But, since we got that fixed and the span started working, I felt that
timing wasn't the source of the problem. Plus, if we dump the error
counters on both ends, they are not incrementing... even if the span is
up for several days and we clearly have the audio problems. The slip
counters, framing error, etc all stay at 0 and you would figure that if
it was timing slip, those would be incrementing on at least one of the
sides.

J.
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