[cisco-voip] fax problems with FXS as well?

[Fred Nielsen]

If your underlying network is okay to support fax-passthrough (meaning
rather low latency/jitter), than most of these platforms will work okay for
fax.  ATAs seem to be the sole exception, as they do not perform fax
detection very reliably in my experience.  If you are needing to support
fax-relay of some sort, then the VG224/FXS port adapter seems the clear
choice to me, though the VG248 has some capability in this area as well.
 
Bottom line, trying to support transmissions that are regularly in excess of
19.2 kbps put out by a high-speed fax (Super-G3) is difficult to support
when you have to repackage the analog signal over IP... regardless of the
platform and transport type you choose.  This is just my experience.  Cisco
is continously improving support for fax-relay, but in practice I've found
that fax-passthrough is still the most universally reliable way to get the
job done.
 
Without getting into the numerous specifics of where each platform stops, I
would rank them in loose capability for fax/modem transmissions as follows,
from least to most:
ATAs
VG248
VG224
FXS adapters in late model routers/modules (i.e. ISR or NM-HD-2V) 
 
-- Fred Nielsen

  _____  

From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Lelio Fulgenzi
Sent: Thursday, November 30, 2006 11:41 AM
To: cisco-voip at puck.nether.net
Subject: [cisco-voip] fax problems with FXS as well?


I know that people have been having problems with faxing and VG224/VG248 and
ATAs ..... but are these problems averted by using FXS ports? The problems I
am referring to is the inability of these machines to talk to other high
speed faxes (which I guess are auto negotiating).
 
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Lelio Fulgenzi, B.A.
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
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"I can eat fifty eggs." "Nobody can eat fifty eggs."
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