BenQ HERC1 900 User Manual page 32

Forward
Allows two parties to connect, while ending one's own call
(one of the two parties may be involved in an active call
while the other is either on hold or being dialed), so as to
allow the two parties to have their own call.
Send DTMF
When the phone is connected with other devices or services,
you can send DTMF (Dual Tone Multi-Frequency) strings.
DTMF strings are keypad tones that can be sent via the
microphone as you dial another number. Your phone will emit
the tones in order to communicate with answering machines,
pagers, computerized telephone services, and so forth.
Enter the number and then press
string.
End Call
End All
Ends all calls, whether active or on hold.
End Active
Ends only the active call.
End Hold
Ends only a call or calls on hold.
End One
Ends only a single call by the number or the contact.
Hold/Unhold/Swap
Toggles the call status.
18 Using Your Phone
to send the DTMF