Fax Tones And Handshake; Ecm (Error Correction Mode) - Brother FAX-645 Owner's Manual

Fax Tones and Handshake

When someone is sending a fax, the FAX/MFC 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/MFC 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/MFC 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/MFC answers in FAX/TEL (F/T) Mode, the FAX/MFC listens for
CNG tones and then responds with receiving tones. This mode is best suited to
conditions where you want to man the FAX/MFC.
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/MFC.

ECM (Error Correction Mode)

The Error Correction Mode (ECM) is a way for the FAX/MFC 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. ECM by default
is set ON.
Sufficient memory must be available in your FAX/MFC for this feature to work.
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