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Re: [hylafax-users] What happens to faxes that fail the PercentGoodLines test?
On 2002.04.02 23:14 Dustin Puryear wrote:
> At 10:53 PM 4/2/2002 -0800, you wrote:
>>> I realize there is an obvious trade-off here.
>> If there is a problem with HylaFAX it is that it expects the sender's
>> fax to make use of RTN, so it deletes the corrupt page and expects a
>> replacement to come. The problem with that assumption is that some
>> senders out there don't make use of our RTN signal.
> So it is possible that Hylafax will delete a corrupt page and the sender
> will never know?
Yes. If their system doesn't look for, handle, or hear (for whatever
reason) our RTN signal, then the remote will likely just hang up, believe
that we got the fax just fine, and faxgetty would have deleted the
corrupted page already. From what I know, faxgetty isn't expecting this
behavior, so there's no way to tell faxgetty, "wait until they start page
re-transmission before deleting the corrupted page". I'd venture to guess
that this was designed like this on purpose to avoid timing problems.
> Taking this to the worst case, if a one page fax is sent then we could
> miss the entire fax and the sender wouldn't be aware of this?
Correct. FaxMaster will know, though, that the fax was attempted and
failed, and can probably judge from the TSI where it was coming from.
> Does this happen even if the receiving fax were a stand-alone machine
> rather than Hylafax?
Yes, sometimes. That depends on the system. Worse are the fax machines
that don't do *any* copy quality checking and have no capability to send
RTN at all. These machines will often get totally illegible pages with no
Cover sheets are important (and widely used) for this reason. Faxing is
not a 100% trustworthy delivery mechanism. RTN is designed to assist in
delivery success. If a sender wants to ignore T.30's redundancy checks,
then no equipment can compensate for it.
> Basically, if the sending fax machine ignores RTN then shame on them?
Pretty much. If they're not going to pay attention to our
acceptance/rejection of the image quality, then they should expect to have
sending problems. Except for possibly delivering a corrupted image to
FaxMaster, I don't know what more can be done on our side. Most of the
times these corrupted pages would be so badly distorted that they would be
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