Panasonic KX- TC1721B Operating Instructions Manual page 24

24
= Making Calls
What the line indicator means
o You are using the line on the handset.
Flashing twice Someone else is using the line on the handset
every 2 seconds or parallel connected telephone.
Flashing A call is on hold.
Flashing quickly A call is being received.
Lighted handset keypad
The handset dialing buttons will light when you press a button or lift the
handset off the base unit, and flash when a call is received. The lights will
go out about 10 seconds after pressing a button, lifting the handset or
answering a call.
Backlit LCD display
The lighted display will stay on for about 10 seconds after pressing a
handset button or lifting the handset off the base unit.