[VoiceOps] Dynamic T1 Faxing over IP
josmon at rigozsaurus.com
Fri Dec 17 01:27:08 EST 2010
On Wed, Dec 15, 2010 at 04:53:54PM -0600, Jeff Anderson wrote:
> We are experiencing a fair amount of heart burn attempting to support faxing
> over our Dynamic T1 product. Some customers it works great and others have
> frequent problems.
A little dated, but decent:
As you've seen -- it *can* work. But the heartache and pain is
unbelievable in the real world when you can't control the entire
conversation (both FAX machines *AND* the network between them).
Part of it lies in the speeds the FAXes try to negotiate over a
G.711 link. If you can convince people to set their FAXes to 9600,
you'll get better results.
Another issue is that FAXes send image info inside a continuous signal
envelope -- if there is any interruption (lost packets), they drop the
connection. You don't just lose part of the image, you lose the rest of
Other issues crop up as well -- but speed and minor interruptions are
the big killers of FAX.
T.38 should help -- by terminating the envelope in the ATA, then
transporting the image info packetized, and rebuilding an envelope at
the other end -- but the myriad of T.38 implementations/versions make it
difficult to trust that it will work.
In my former life, we did as many here suggest -- get a POTS line for
people that *must* have FAX/Modems running. They'll thank you in the
More information about the VoiceOps