Aastra 9480i CT User Manual page 207

IF
An incoming call comes in on another line (NOT in
focus), and the disconnected screen is displaying on
the line in focus,
A phone application is NOT in focus,
The following procedure describes how to handle the disconnected screens on your phone.
IP Phone UI
Goodbye
1. Press the Goodbye
The busy tone stops and the disconnected screen no longer displays.
or
Select any Line key.
The busy tone stops and the disconnected screen no longer displays.
A dial screen displays.
41-001381-00 REV01 – 06.2013
THEN
the disconnected screen no longer displays on the line in focus.
busy tone plays
no disconnected screen displays
When the phone application in focus on screen stops:
busy tone plays
disconnected screen displays
key.
Available Features Enabled by Administrators
199