[geeks] fax from Solaris and/or Linux?

[Mouse]

> Fax over IP is really ugly.  There are two protocols: T.37 and T.38.
> One is store-and-forward, the other is real-time.  Both are really
> poorly supported.

There exist ATAs that support T.38, in the sense that they speak the
usual POTS fax protocol (T.4/T.30, I think?) over their PTOS port and
then speak T.38 over SIP out the other side.

> Don't try to fax over a VOIP line.

That matches my own experience, but see below.

> VOIP codecs are designed to compress all of your fax data out of the
> signal.  It's very unreliable.

This is a problem with codec choice, not a problem with VoI[%].  One of
my employers does VoI telephony and usually uses G.711, which is
basically "no compression".  (It does mu-law range compression, but no
inter-sample compression.)  I once did some tests; I found that
conventional faxing works fine with traditional fax machines over
SIP/RTP with an ATA speaking G.711, _provided_ there is no packet loss.
With packet loss, even as little as a single packet, it usually falls
over rather hard (about the best case I saw is losing a few mm of
scanlines).  The usual fax codecs are designed to deal with the errors
POTS typically introduces, which are very different from the errors VoI
typically introduces - that's why T.38 exists (it's designed for the
sorts of errors IP telephony typically introduces).

[%] VoIP has been used for a lot longer than most people realize, just
    not in ways visible to the end user.  What's new is doing VoIP over
    the open Internet; it really should be called VoI, Voice over
    Internet.

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