Asterisk: The Definitive Guide, 4th Edition

Chapter 19. Fax

Have no fear of perfection. You’ll never reach it.

—Salvador Dali

The concept of facsimile transmission has been around for over 100 years, but it was not until the 1980s that the use of fax machines became essential in business. This lasted for perhaps two decades. Then the Internet came along, and very shortly after that, the fax quickly became almost irrelevant.

What Is a Fax?

A fax machine allows a facsimile (copy) of a document to be transmitted across a telephone line. In the Internet age, this sort of functionality seems useless; however, prior to ubiquitous Internet access, this was a very useful thing indeed. Fax machines scan a document into a digital format, transmit the digital information in a manner similar to that used by an analog modem, and then convert and print the received information on the other end.

Ways to Handle Faxes in Asterisk

Asterisk offers the ability to both send and receive faxes, but it should be noted that Asterisk is only doing the basics of fax transport. This means that providing a complete experience to your users will require external programs and resources beyond what Asterisk delivers.

Asterisk Fax can:

• Recognize an incoming fax connection and negotiate a session

• Store (receive) the incoming fax as a Tagged Image File Format (TIFF) file

• Accept TIFF files in a fax-compatible format

• Transmit TIFF files to another fax machine

Asterisk Fax cannot:

• Print faxes

• Accept documents for transmission in any format other than TIFF

Receiving is relatively ...