AT&T MERLIN LEGEND System Reference Manual page 237

Features
2-188 Group Calling
The system does not block the programming of any station jack (including
station jacks used for telephones or system operator consoles) as an
external alert that provides Calls-in-Queue Alarm indication. However,
programming a telephone as a Calls-in-Queue Alarm is not recommended
since the telephone rings continuously while the number of calls in the calling
group queue is equal to or greater than the programmed threshold.
A calling group or QCC queue can be a receiver for one or more Overflow
Coverage groups. Only one calling group or QCC queue can be assigned as
a receiver for each Overflow Coverage group.
Extension Status must be set to Calling Group/CMS (the factory setting) and
not hotel configuration.
The lntegrated or Generic VMl group type cannot be assigned to a calling
group used for fax machines.
Individual calling group member stations are assigned an extension number,
which allows a group member to receive calls as an individual as well as a
group member.
When calling group members make a call to their own calling group, the call
is not delivered to that group member since he or she is considered
unavailable while making the call.
To allow all calling group members' stations to ring when an outside call is
not answered within three rings, the lines/trunks programmed to ring into the
queue can also be assigned to buttons on calling group members'
telephones and programmed for delayed ring. This does not work for inside
calls, Remote Access calls, and direct inward dialing calls, or if a delay
announcement device is assigned to the group.
Lines/trunks that are programmed to ring into a calling group also ring at any
telephones that have the line/trunk assigned to a button. If a call is answered
at anyone of these telephones, the call is removed from the calling group
queue.
A line/trunk cannot be programmed to ring into more than one calling group.
A line/trunk cannot be programmed to ring into both a calling group and a
QCC queue.
If no line/trunks are assigned to the calling group, only inside calls are
eligible for calling group distribution.
Calls are not sent to an overflow group's queue and therefore are not eligible
for that group's Overflow Coverage.
The delay announcement is not played when a call is returned to the queue
after being sent to a calling group member who does not answer.
Any multiline telephone in the system can be used to monitor the status of a
calling group's queue by programming the Calls-in-Queue Alarm button. An
MLX display telephone can be used to view the number of calls in a queue
(1-99) on the display by pressing the Inspect button and then pressing the
Auto Dial button programmed with the calling group's extension number.
The calling group supervisor can log in or log out delay announcement
devices.