Brother FAX 1840C - Manual (Page 86)

QUICK-DIAL NUMBERS AND DIALING OPTIONS 5 - 7
Tone or Pulse
If you have a Pulse dialing service, but need to send Tone signals
(for example, for telephone banking), follow the instructions below. If
you have Touch Tone service, you will not need this feature to send
tone signals.
1
For Fax-1840C and FAX-1940CN, lift the handset.
—OR—
For MFC-3240C and MFC-3340CN, lift the handset of the
external phone.
2
Press # on the machine’s control panel. Any digits dialed after
this will send tone signals.
When you hang up, the machine will return to the Pulse dialing
service.