Attrafax FoIP stack

Attrafax is now released under a dual license (GPL/Commercial) - read the full press release here:

As a first move in supporting the open source community, we decided to open source the stack previously used by the Attrafax product (and used in Zoiper in a slightly modified form).
The fax solution consists of a T.30/T.38 stack, with an example implementation for Asterisk (including gatewaying support).

Supported standards:

  • ITU-V V.21 V.27ter V.29 V.17
  • V.27ter (2400 and 4800bps)
  • V.29 (7200 and 9600bps)
  • V.17 (7200, 9600, 12000 and 14400bps)
  • ITU-T T.4 T.30

The example implementation for Asterisk is currently for a slightly outdated version of Asterisk, if somebody feels like porting it to a newer version of Asterisk, let us know and we will host it on the website.
We have some more unused IP laying around that we might release to the general public in the coming months. (Stay tuned!)
Attrafax relies on these 3rd party projects: libtiff, libjpeg, libz, openssl, Asterisk (for the example implementation).

Zoiper users can send and receives faxes directly from their desktop, through tiff files or by printing to Zoiper from any application.

For more information, have a look here:

Sending and receiving faxes with Zoiper Classic
Sending and receiving faxes with Zoiper Communicator
Printer driver installation tutorial

People that are interested in commercial support, a commercial license or acquiring the ownership rights can contact us here

Download information

You can download the Attrafax tarball from here. We also have a tarball without asterisk source.
Klaus Darillion contributed this untested patch for asterisk, let us know if it works for you.
Fixed point patches by switchfin here
Patch for Asterisk 1.4.35 by "Cache" and "bird_of_Luck" download link here

Installation instructions

After downloading the tarball, the first thing you need is to compile the library (libt30). To do that, simply run "".

Then you need to build a patched asterisk. There are two options for this - either configure and build the asterisk in src/asterisk in the tarball, or use the provided patch in patches/ to patch one for yourself. There's no difference in building it than the normal asterisk in this regard.

Last, you need to build the asterisk modules. Just go to src/modules and run make && make install - this will build them against the locally installed asterisk and install them in the proper directory.

More information can be found in the doc/ directory of the archive.

Questions ?

Q: How does this compare to FAX for Asterisk or spanDSP?
A: It is more of the same, but adds transparent gateway functionality as well. We do not have a comparison on robustness and interoperability. We will leave that up to the community.

Q: Is this an Asterisk fork ?
A: No, this is merely a branch with an alternative fax functionality. As a general rule we will not accept any patches that are not related to our fax stack or the standard Asterisk (or other PBX projects) versions.

Q: Will this be merged into Asterisk / Freeswitch / Yate source tree ?
A: We are open to discuss this possibility with the copyright owners for those projects, at this time we cannot tell what the future will bring.

Q: Is this based on spanDSP ?
A: No, the attrafax solution is not using spanDSP, if you are looking for spanDSP have a look here:

Q: Will this work with FreeSwitch / Yate etc ?
A: No, out of the box it will not work, but with some extra integration work, it can be made to work with those. If you succeed in combining them, lets us know and we will include the howto / patches on our website.

Q: It does not seem to work very well for us, what could the issue be ?
A: Most likely the issue will be with line levels that are too low or too high, or frame slips occur. Please measure your line levels

Q: If i buy a commercial license for Attrafax, can i sell it in a closed source form ?
A: Yes, you can, however keep in mind that if you also want to use the Asterisk implementation example that you will need a commercial license for Asterisk as well from the Asterisk copyright holder, Digium

We are not related to Asterisk, Digium, Yate, Freeswitch, All trademarks and copyrights on this website are owned by their respective trademark and copyright holders.