[Asterisk-Users] Re: Asterisk in production as a fax server, anyone?

[Olivier Krief]

2006/3/30, Don Pobanz <asterisk at hastingsutilities.com>:
>
> Adolfo R. Brandes wrote:
> > Lee Howard wrote:
> >> However, based on the comments you give I'd suspect that you're having
> >> what people seem to be calling "frame slipping".  There seem to be
> >> some motherboards that react poorly with Zap cards (or their
> >> respective drivers) and cause that.  Your zttest results should be
> >> revealing here.
>
> Frame slips are NOT motherboard related!
>
> A Frame slip is due to clocks at opposite ends of a circuit such as a T1
> running at different speeds. Either a buffer overflows and one frame is
> thrown away or there is no data when a frame is needed so the previous
> frame is repeated.
>
> The solution is to have one end of the circuit supply the clock and the
> other end derive the clock from the incoming signal.
>
> Don Pobanz


How would you check clocks speeds at opposite ends of a circuit (T1, E1,
BRI, ...) ?

As it seems frame slips occur from time to time (for instance, on 10% of
received faxes), do you imply that Asterisk settings should be changed so
that on every fax received, it should adopt opposite clock speed (unlike
today where by chance, 90% of circuit clock speeds are the same) ?

Regards


Olivier
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