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INTRODUCTION
1 - 2
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.