FreeSWITCH can transmit electronic documents to a destination fax machine. Only TIFF documents can be transmitted. However, it is possible to convert a number of formats (for example, PDF) to TIFF. This recipe will discuss some common and freely available tools.
In simple terms, sending a fax requires only a few things such as a TIFF file, gateway, and destination fax machine (for testing purposes, you can download a sample TIFF file from http://files.freeswitch.org/txfax-sample.tiff). Put your TIFF file into a known location. For our example, we will use /tmp/txfax-sample.tiff. The gateway is your connection to the PSTN, and the fax machine will simply be the device that answers your outbound phone call. Even, if you do not have a gateway or a fax machine handy, you can still try out this recipe by having FreeSWITCH send the fax to itself using the fax_receive extension in the default dialplan.