Brother FAX 770 - Manual (Page 13)

3
I N T R O D U C T I O N
When your FAX/MFC answers in FAX/TEL Mode, the FAX/MFC 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/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.
Sufficient memory must be available in your FAX/MFC for this feature to
work.