AT&T MERLIN LEGEND Release 4.0 Feature Reference page 290

Feature Reference
A single-line telephone user can put a call on hold by sending a switchhook
flash: pressing and releasing the Recall or Flash button or the switchhook,
depending on the telephone model. If a single-line telephone user with a call on
hold hangs up, the call rings back at the extension.
NOTE:
Some single-line telephones, such as AT&T models 2500YMGL, 2500MMGK,
and 8110M, use a timed or positive disconnect. On these telephones, pressing
the switchhook disconnects the call. Use the Recall or Flash button instead of
the switchhook to send a switchhook flash. (The 8100M telephone must have
positive disconnect programmed on the telephone as described in its manual.)
Feature Interactions
Auto Dial
Basic Rate Interface
Call Waiting
Conference
290
Hold
The Hold button is used to enter the Pause special character in a
telephone number programmed on an Auto Dial button.
An active call on a BRI line can be placed on hold by using the MERLIN
LEGEND Hold feature. All call appearances (such as LEDs) are the
same as for other non-BRI lines.
A person with all calls on hold cannot hear the call-waiting tone.
When adding other participants to a conference, the conference
originator hears the hold reminder if the conference is on hold for longer
than one minute (if the originator is a telephone user) or for longer than
the operator hold timer setting (if the originator is an operator).
If DLC Operator Automatic Hold is programmed and used by a DLC
operator while setting up a conference, the entire conference goes on
hold.
Both parties on an inside call cannot put each other on hold. If a user
presses the Hold button while waiting on hold for a conference initiated
by another user (an inside call) or if the user presses the Conf button
while waiting on hold on an inside call, the entire conference call is
disconnected.
The initiator of a conference call can leave the conference by touching
Hold. The conference initiator can rejoin the conference call by
touching the line button of any conference participant.
In Release 2.1 and later, a call that has been put on hold on a Cover
button can be added to a conference by a user who has a personal line
for the call.