Fax Tones and Handshake; ECM (Error Correction Mode); 1 - 2- Page 15

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T7BASE-US-FM5.5

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.

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.

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.