Aastra OpenCom 100 Series Mounting And Commissioning User Manual page 211

Call Queue
If attendants leave the station, they sign off from the hunt group by means of a
feature key. In contrast to Example 1, further calls do not have to be processed after
the sign-off, as the calls are also registered in the queues of the other signed-on
enquiry stations.
Note
When the last enquiry station remaining in the hunt group signs off, further callers
will hear the busy tone.
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