Brother MFC-640CW - Manual (Page 182)

A - 9 APPENDIX A
Connecting an external device to your
machine
Connecting an external telephone
You can connect a separate telephone (or telephone answering
device) directly to your machine as shown in the diagram below.
Connect the telephone line cord to the jack labeled EXT. in the left of
the machine.
When you are using an external or an extension phone, the LCD
shows Ext. Tel in Use.
Connecting an external telephone answering
device (TAD)
Sequence
You may choose to connect an additional answering device.
However, when you have an external TAD on the same telephone
line as the machine, the TAD answers all calls and the machine
“listens” for fax calling (CNG) tones. If it hears them, the machine
takes over the call and receives the fax. If it does not hear CNG
tones, the machine lets the TAD continue playing your outgoing
message so your caller can leave you a voice message.
Extension
Telephone
External
Telephone