Fax Tones and Handshake; ECM (Error Correction Mode)- Page 12

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C H A P T E R

O N E

Fax Tones and Handshake

When someone is sending a fax, the fax machine sends fax calling tones (CNG
tones)—soft, intermittent beeps at 4-second intervals. You’ll hear them when
you dial and press 

Start

, and they continue for about 40 seconds after dialing.

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’ll soon learn to listen for these
soft beeps each time you answer a phone on your fax line, so you 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

.

When your fax machine answers in FAX/TEL Mode, the fax machine listens
for CNG tones and then responds with receiving tones.

The fax “handshake” is the time in which the sending machine’s CNG tones
and the receiving machines “chirps” overlap. This must be for at least 2 to 4
seconds, so the 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 40 seconds after the number is dialed. Therefore, it’s
important for the receiving machine to answer the call in as few rings as
possible.

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.

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 fax machine for this feature to
work.