Palm Treo 755P User Manual page 74

Places the current call on hold.
Enables you to place another call while the first call is on hold. For
information on handling a second outgoing call, see "Making a Second
Call" on page 69.
Opens the Dial Pad so you can manually dial additional numbers, such
as an extension or a response to a voice prompt.
Dials any extra digits (such as a password or an extension) that you
assigned to a favorite button. This button replaces the Dial Pad button
during outgoing calls to numbers that include predefined extra digits.
See "Defining Favorite Buttons" on page 74 for information on defining
extra digits.
Mutes the microphone so that you cannot be heard.
Tip:
Ending a Call
Do one of the following to end a call:
Press Power/End
Select Hang Up All.
Press the button on the headset (if the headset is attached).
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To avoid accidentally pressing onscreen buttons while holding the device
to your ear, you can disable the screen's touch-sensitive feature during
your calls (see "Locking Your Screen" on page 274).
.
Section 2B: Phone Features