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92 Chapter 14
About Fax Machines
If you are a first-time fax machine user, fax operation might seem a little mysterious. You will soon
get used to the unusual fax tones on your phone line, and be able to send and receive faxes easily.
Fax Tones and Handshake
When someone is sending a fax, the fax machine sends fax calling tones, (CNG tones)—soft, beeps
at 4-second intervals. You will hear them when you dial and press Fax Start, and they continue for
about 60 seconds after dialling. During that time, the sending machine must begin the “handshake”
with the receiving machine. Each time you use automatic procedures to send a fax, you are sending
CNG tones over the phone line. You will soon learn to listen for these soft beeps each time you
answer a phone on your fax line, so you can know if you are receiving a fax message.
The receiving fax responds with fax receiving tones—loud, chirping sounds. A receiving fax chirps
for about 40 seconds over the phone line, and the screen displays RECEIVE. If your fax machine
is set to the FAX ONLY Mode, it will answer every call automatically with fax receiving tones.
Even if the other party hangs up, your fax machine continues to send the “chirps” for about 40
seconds, and the screen continues to display RECEIVE. To cancel the receiving mode, press
Stop/Exit.
When your fax machine is in FAX/TEL (F/T) mode, it answers with a short beep. After this beep,
the fax machine listens for CNG tones, and, if heard, it will respond with receiving tones.
The fax “handshake” is the time in which the sending machine’s CNG tones and the receiving
machine’s “chirps” overlap. This must be for at least 2 to 4 seconds, so the fax machines can
understand how each is sending and receiving the fax. The handshake cannot begin until the call is
answered, and the CNG tones only last for about 60 seconds after the number is dialled. Therefore,
it’s important for the receiving machine to answer the call in as few rings as possible.
ECM (Error Correction Mode)
The Error Correction Mode (ECM) is a way for the fax machine to check the integrity of a fax
transmission while it is in progress. ECM transmissions are possible only between machines that
both have the ECM feature. If they do, you may send and receive fax messages that are continuously
checked for their integrity.
Sufficient memory must be available in your machine for this feature to work.
When you have an external telephone answering device (TAD) on your fax line,
your TAD will determine the number of rings before the call is answered. Pay
special attention to the directions in the Installation chapter for connecting a TAD
to your fax machine.