Sharp FO-475 Operation Manual page 18

Connections
Handset
Connect the handset as shown and place it on the handset rest.
The ends of the handset lead are identical, so they will go into either
socket.
Make sure the
handset cord goes
into the unmarked
socket on the side of
the machine!
6
Use the handset to
make ordinary phone
calls, or to transmit
and receive
documents manually.