About Fax Machines; Fax Tones And Handshake; Ecm (Error Correction Mode) - Brother MFC9100C Service Manual

About Fax Machines

If you're a first-time fax machine user, fax operation might seem a little
mysterious. Soon, you'll recognize 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 MFC sends fax calling tones, (CNG
tones)—soft, intermittent beeps at 4-second intervals. You'll hear them
when you dial and press
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 MFC 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 RECEIVING. If your MFC is set to the FAX
mode, it will answer every call automatically with fax receiving tones.
Even if the other party hangs up, your MFC continues to send the "chirps"
for about 40 seconds, and the screen continues to display RECEIVING.
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 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 last for only 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
MFC line, your TAD will determine the number of rings before the call is
answered. Pay special attention to the directions in the Assembly and
Connections chapter for connecting a TAD to your MFC.

ECM (Error Correction Mode)

The Error Correction Mode (ECM) is a way for the 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.
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, and they continue for about 40 seconds after
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