Panasonic KX-PRX120AZ Operating Instructions Manual page 21

Allows you to make intercom calls
Allows you to change certain features of your phone system
Allows you to use the phone system's answering system (KX-PRX120 only)
Allows you to access the base unit's call log
Allows you to use the base unit's key finder feature
Starting the [Landline] app
Tap [Landline] in the home screen or app list.
Getting Started
21