AT&T MERLIN LEGEND System Reference Manual page 117

Features
Direct-Line Console
Display
Forward and Follow Me
Group Calling
Hold
Paging
Personal Lines
Pickup
Queued Call Console
2-68 Call Waiting
When the DLC system operator uses Camp-On to transfer a call to a busy
extension, the call is placed in the Call Waiting queue and the caller hears the
Call Waiting tone whether or not the extension has the Call Waiting feature
activated.
If the system is programmed for One-Touch Transfer with automatic completion,
the system operator uses Camp-On by pressing the Transfer button, dialing the
extension manually, activating Camp-On, hanging up, and pressing another line
button or the Transfer button again. If the system operator presses an Auto Dial
or DSS button, the transfer is automatically completed and Camp-On cannot be
used.
When a user has a call aiting "Call-Waiting" is-shown on the display.
W
Call Waiting does not apply to forwarded calls since the system tries the
destination telephone instead of the forwarding telephone. However, if the call is
not forwarded for any reason (the line/trunk selected is an unreliable loop-start
line/trunk), call waiting functions normally.
Calls made to a calling group are not eligible for Call Waiting since the call rings
into the calling group's queue. However, call waiting can be used for calls to
individual members of the calling group.
A person with all calls on hold cannot hear the Call Waiting tone.
Call Waiting cannot be used for Group Paging calls to busy extensions.
A user does not hear a Call Waiting tone for calls received on a personal line
unless the business subscribes to the Call Waiting service from the local
telephone company.
Pickup features cannot be used to answer a waiting call at another telephone.
QCC system operators are not eligible for Call Waiting.
A QCC system operator can release a call to a busy extension by selecting
Camp-On from the display or by pressing the Release button. If Camp-On is
used, the call does not return to the QCC queue until the Camp-On return
interval expires. If the system operator presses the Release button, the
extension being called receives the Call Waiting tone (not Camp-On) and the
call returns to the QCC queue when the Transfer return interval expires.
If the system is programmed for automatic extended call completion, to use
Camp-On, the system operator must press the Start button, dial the extension
manually, activate Camp-On, and press Release. If the system operator presses
a DSS button, the transfer is automatically completed and Camp-On cannot be
used.