System information

Asterisk Fax cannot:
• Print faxes
• Accept documents for transmission in any format other than TIFF
Receiving is relatively simple, since the format of the document is determined at the
sending end, and thus all Asterisk needs to do is store the document.
Transmitting is somewhat more complex, since the transmitting end is responsible for
ensuring that the document to be sent is in the correct format for faxing. This typically
places a burden on the user to understand how to create a properly formatted docu-
ment, or requires complex client or server software to handle the formatting (for ex-
ample, through a print driver installed on the local PC) and placement of the fax job
in a location where the server can grab it and transmit it.
spandsp
Initially, the only way to handle faxing in Asterisk was through the spandsp library.
spandsp provides a multitude of Digital Signal Processing (DSP) capabilities, but in this
context all we are interested in is its fax functionality.
Asterisk has the hooks built in to make use of spandsp, but due to incompatible licenses,
the spandsp libraries must be downloaded and compiled separately from Asterisk. Also,
since spandsp was not written only for Asterisk, it will not assume that it is being
installed for Asterisk. This means that a few extra steps will be required to ensure
Asterisk can use spandsp.
Obtaining spandsp
As of this writing, the current version of spandsp is 0.0.6.
Download and extract the spandsp source code as follows:
$ mkdir ~/src/asterisk-complete/thirdparty
$ cd ~/src/asterisk-complete/thirdparty
$ wget http://www.soft-switch.org/downloads/spandsp/spandsp-0.0.6pre17.tgz
$ tar zxvf spandsp-0.0.6pre17.tgz
$ cd spandsp-0.0.6
Compiling and Installing spandsp
The spandsp software should compile and install with the following commands:
$ ./configure
$ make
$ sudo make install
444 | Chapter 19: Fax