We're Looking at creating a large fax farm via T.38 (Fax over Voip - hundreds of incoming and outgoing faxes) on linux servers, anyone have any suggestions on what is available? All my searches return using Asterisk 1.6.x with a commercial product from Digium called "Fax for Asterisk" (with required purchase of "channels" at $38.00 per channel). There must be an open source project out there I can't seem to find.

Suggestions welcome!

Here is some additional info: We're using Ubuntu 9.10, and planning to use T.38

If I have missed anything, let me know.


Since I am the author of the howto mentioned above I can verify that it does actually work. (It doesn't need AvantFax however)

Brian, you are correct for the most part, however there are a few issues to note. Initially t38modem 1.0 cannot register on a remote SIP server, thus it cannot be used on any SIP Peer that requires authentication. (You need to use t38modem 1.2.0, which actually supports SIP registration, but fails in incoming faxes). Additionally I am not that sure that it can perform digest authentication as well, so it might not work for outgoing calls as well.

Also the use of an Asterisk server offers better control of the calls going in and out of the t38modems. Imagine a scenario where you need behind a single number to have 20-30 or even 50 t38modems answering a call, you need something in front to actually perform the allocations. Let alone that t38modem is a rather unstable piece of software (especially in it's 1.0 version). By having an asterisk in front you are able to retry a different modem if one fails to answer without hanging up the line.

Let alone things like changing the A-number/B-number depending on caller or destination called.

Well anyhow, it's a nice setup :)


Fax and Asterisk/HylaFax was never a good solution when my consulting company tried to implement it at a few places. We eventually gave up and went to plain old fashion fax machines.


Have you seen Hylafax?

  • you need something to turn Hylafax into T38... – Brian Postow Apr 21 '10 at 16:01

you can use Hylafax combined with AvantFax and Asterisk. Here you can find the step by step guide


  • That uses T38modem. in that case, what's the point of Asterisk? If Hylafax and T38modem will end out T38, why do you need a PBX? (Also AvantFax doesn't seem to be mentioned on that link) – Brian Postow Apr 21 '10 at 16:00
  • Aterisk simulate T38 modem and is used to reach SIP ISP as you ca read on the document. – pirata Apr 21 '10 at 16:03
  • But T38modem puts out T38, so, you have Hylafax sending modem to T38modem, which sends T38 to Asterisk which then sends T38 to the ISP. T38modem should be able to do all of that itself. You don't need Asterisk. – Brian Postow Apr 21 '10 at 20:30

There's an opensource project T38Modem (https://sourceforge.net/projects/t38modem/) that works with Hylafax. It's based on Opal (https://sourceforge.net/projects/opalvoip/) which seems to have a SIP bug at the moment... but once that's fixed, hopefully everything will work again...


Check into Dialogic and their FoIP hardware and software. They bought out many players in the FoIP space (Cantata, Brooktrout). You may want to talk to them directly.

Another alternative is Noojee. Also, if possible, consider a third-party service (like eFax, that has enterprise-level, secure solutions) for accepting faxes and converting them to email or PDFs for delivery into your system(s). That way to remove yourself from having to maintain what will be the most annoying part of your telecom experience.

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