Attrafax, Fax Modems and Modules – Now Released under Dual License – GPL/Commercial

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The fax modems and modules stack used in the popular Zoiper softphone are now open and available under dual license – GPL and commercial

Zoiper Softphone

Zoiper softphone allows you to send faxes from any Windows application.

We decided to open source the stack as a first move in supporting the open source community.

Attrafax is a complete independent implementation of PSTN and over-IP faxing with its very own dedicated set of software DSP modems. While Attrafax is fully compliant with a wide range of standards it is not based on any existing FoIP solution.

The fax library compiles and works under Windows, Linux, Mac OS X, Solaris, and FreeBSD and is fully portable to other platforms. The code is written in portable ANSI C, and has proven to work on 32 and 64-bit platforms.

The Attrafax solution is used in a modified form in the leading Zoiper softphone. The fax sending and receiving functionality is a key feature therefore is available in all the versions of the softphone – Zoiper desktop - free and business and in Zoiper WEB. The fax-supporting softphone is available for download at

The Attrafax fax solution consists of a T.30/T.38 stack, with an example implementation for Asterisk (including gatewaying support) so that it can be deployed in production immediately.
Commercial support is also available.

The supported standards are as follows:

  • 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

Supported platforms:
Linux, FreeBSD
Zaptel, DAHDI, chan_ss7, chan_capi

For over two years now Attrafax has been in production with different service providers, helping them offer a complete FoIP solution. Attrafax has been the preferred feature-rich cost-saving alternative to the standard faxing solutions and hardware for various enterprises, increasing the efficiency of their operations

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The press release can be downloaded from:


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Silvana Pashova

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