[asterisk-users] Terrible clicking on T1

[Kevin Bockman]

Jay R. Ashworth wrote:
> 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

He means to set the Nortel to be the master for timing and Asterisk to 
be the slave.  That means change:

span=1,0,0,esf,b8zs

to:

span=1,1,0,esf,b8zs

.. and whatever you have to do on the Nortel.


Kevin