10.14.3.1. User Interface 
Digital telephones require a Park key with an led.
A call in talk state can be parked by pressing the Park key. All members
of the same pickup group as the parking terminal recieve a visual indication
via the park key led flashing.
A call can be retrieved from Park by any member pressing the park
key
After a congfigurable time-out the Parked call recalls back to the
parking station and signals as a group pickup call ,depending on the
pickup group settings,on other members of the pickup group.