BenQ S660C - Manual (Page 67)

Using Your Phone 53
Send DTMF
When the phone is connected with other devices or services, you
can send DTMF (Dual Tone Modulation 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 phone number and then press
to send the DTMF
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.
Hold/Unhold/Swap
Toggles the call status.
Mute/Unmute
Activates/cancels the silent mode.