AT&T MERLIN LEGEND Calling Group Supervizor's Manual page 13

Calling Group Overview
Both inside and outside calls can come in to a calling group.
Inside callers can reach the calling group on a single
extension. Outside callers dial a special published phone
number that bypasses the system operator and connects
directly to an available agent. The system operator and other
users can also transfer calls to a calling group.
Each agent's phone has its own extension number so inside
callers can dial the agent directly. If your system has direct
inward dialing lines, outside callers can also dial individual
agents directly. Ask your system manager about direct inward
dialing lines.
When all agents in a calling group are unavailable, incoming
calls are placed in a holding area (a queue) where the system
tracks the number of calls and the order in which they arrived.
Depending on your system, callers entering the queue may
hear a recorded announcement asking them to hold and wait
for the next available agent. While waiting in the queue, callers
may hear Music-on-Hold or ringing. As agents become
available, calls are distributed on a first-in, first-out basis.
1-2 Calling Group Overview