Sharp FO-A650 Operation Manual page 16

Connections
Extension phone (optional)
If desired, you can connect an extension phone to the TEL. SET socket on the
fax.
1
Remove the seal covering the TEL. SET
socket.
2
Connect the extension phone line to
the TEL. SET socket.
Note: In New Zealand, not all standard telephones will respond to incoming
ringing when connected to the extension socket of the equipment.
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