Re: flexfax: How to shorten delay when retry occurs?

[David Woolley <david@djwhome.demon.co.uk>]

> 
> Whenever there is an error encountered by the fax server such as NO CARRIER
> DETECTED, it will SLEEP for approximately 15 minutes.

If you are talking about a per job delay, rather than a per modem delay,
the default would appear to be more like 5 minutes (taken from config.h.in).
>From an old copy of the source code, this seems to be an undocumented 
parameter called jobreqother.

However, before changing it you should check the legal position in your
country.  Modems in the UK used to force a minimum interval between retries
of a number.  They no longer do, however the manuals require that modem
and software comply with a document, which I believe imposes the same
requirements.  The last set of these I saw allowed indefinite retries
at 10 minute intervals, but only allowed one fast retry and then only a
very limited number of tries in quite a few hours if the initial attempts
were at less than ten minute intervals.

The reasons for this are:

- silent or calling tone only wrong numbers can be very frightening;

- fast retries can cause denial of service;

- the telephone network is dimensioned for a particular number of 
  simultaneous calls and a particular attempt rate - to do anything else
  would put up the cost of calls, to pay for the extra equipment.

As an extreme example, my ISP used to provide service in Kingston upon
Hull, through a telephone switch owned by a third party.  Hull was the
one exception to the BT monopoly and BT is still not present there.
They had flat rate charging (charge per call) for local calls, and some
users abused this by staying connected all the time.  This meant there
were no free lines.

Eventually the company providing the lines cancelled their contract.
As far as I can tell this wasn't because of simultaneous call capacity
(erlangs), but because people repeat dialing to try to get in were
overloading their system.  (Note that a failed call may still reserve a
partial path through the network, as well as consuming processing resources,
tone decoders, etc.)