[asterisk-users] Terrible clicking on T1

[Steve Davies]

On 8/9/07, Gleim, Jason <jgleim at ats-ohio.com> wrote:
[snip]
>
> 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.

Yes, but the audio artifact might be caused if Asterisk is using a
different internal clock to your hardware card, particularly if
transcoding is occuring. (This would not cause errors on the card, but
would cause distortion)

A standard E1/T1 install will have the Telco providing clock to your
E1/T1 card, which then acts as the master clock to Asterisk. See the
email from Kevin Bockman previously in this thread - I believe he has
the answer.

Cheers,
Steve