[cisco-voip] reliable FAX over IP

[Andre Beck]

Hi,

On Tue, Nov 14, 2006 at 07:26:24PM -0600, Curt Shaffer wrote:
> I am looking for an ATA that has had very reliable results when 
> passing FAX over IP.

AFAIK there is no such thing. I expect a quality that is identical to
a fax machine connected to an ISDN terminal adapter, as an ISDN B-
channel should behave identical to a G.711 channel. In reality, you
have all sorts of problems, especially at higher fax speeds. This is
ridiculous and nobody could yet explain to me why the hack they don't
make working ATAs.

> I was thinking of testing the Cisco 
> ATA 186 I1, ATA 186 I2, ATA 188 I1. This is what I'm looking for:

AFAIK the 188 is EOL. The 186 I1/I2 will work to some satisfactory
degree given all else is well (G.711 enforced, playout delay and
echo cancellation modified), but they are not hassle free. Stay
away from L-models:

http://www.cisco.com/en/US/products/hw/gatecont/ps514/products_field_notice09186a0080094af7.shtml
 
> Remote FAX -> PTSN -> CME -> over IP via SIP -> ATA -> Fax Machine

I don't know about SIP. With Skinny on CME 4.x you have a working
fax passthrough feature that somehow gets most faxes done, albeit
it's slow. Before CME 4.0 getting somewhat reliable fax was a nightmare
that involved H.323 loads on the ATAs including sophisticated and error
prone configuration thereof. Now at least it's on par with CCM.
 
> What have been the good/bad results you all have seen?

The holy war against faxes is destructive to your nerves. If you think
you finally have it, a new issue will always pop up. Some peer faxes
will never talk to you (essentially because they are broken too, but
explain that to a customer who just swapped an old ISDN PBX for an
IPT solution and *knows* that it still worked yesterday). Users will
be annoyed because of slowness and failures in faxes. And there seems
to be *no* way to fix it. I'm even having issues with T.37 OnRamp, so
it appears there's something rotten at the roots. And it's *not* the
PSTN.

-- 
                  The _S_anta _C_laus _O_peration
  or "how to turn a complete illusion into a neverending money source"

-> Andre Beck    +++ ABP-RIPE +++    IBH Prof. Dr. Horn GmbH, Dresden <-