AT&T MERLIN LEGEND MLX-20L Supervisor Manual page 50

Features
Overflow Coverage
To prevent long delays, the system can be set up so that
calling group calls waiting in queue can be sent to another
calling group or to the system operator in systems with QCCS.
When the number of calls reaches the programmed limit, calls
are sent to the overflow calling group or the QCC, starting
with the call that has been in the queue the longest, until the
number of calls drops below the programmed limit.
Calls are sent to overflow coverage when the following
conditions exist:
The number of calls in queue equals or exceeds the
programmed overflow coverage limit.
An operator is available to receive calls sent to a QCC.
The overflow calling group has an available agent.
If any of the conditions are not met, the call continues to wait
in the original calling group queue until a calling group agent
is available or until the overflow conditions are met and the
call can be directed to the overflow calling group.
Call Queues
3-7