Panasonic KX-T4300BA - Manual (Page 30)

Turning on the answering
system
Confirm that the ANSWER ON indicator light is on when you want to
use the answering system (e.g. before leaving home).
When the answering system is on, the ANSWER ON indicator light is
on and the unit receives an incoming call, plays back the greeting
message and records the callers’ messages.
Before using the answering system feature, you should record your
greeting message. See pages 12-13.
Basic operation