At the moment of preemption the display will change from the information
about "old" connection to an information, that a precedence call is waiting:
"Prioritaetsanruf wartet"/"Precedence call waiting", and the user will
be connected to preemption notification tone. After the called party
has gone on-hook and rering starts, the display will be the same as in
ringing state.
IMPORTANT:
The attendant console is implicitly protected
against preemption by precedence calls.