MX-1800N (serv.man44). Fax Guide (Supplied as pdf file on m c's Hard Disk Drive). - Sharp Copying Equipment User Guide / Operation Manual. Page 123

You can connect an existing extension phone to the machine.
The phone can be used for voice calls and to start fax reception on the machine.
As an example, you can make a phone call using the existing phone, speak to the other party, and then press the 
[BLACK & WHITE START] key (

) to fax an original that has been placed to that party. You can also press the 

[BLACK & WHITE START] key (

) when an original is not placed to receive a fax.

Connect the extension phone as shown below.

   

• Connect an extension phone that has a modular socket. Use standard phone line cable to connect the phone. If other than 

a standard phone line cable is used, the connection may not work correctly.

• If the plug on the telephone line cord does not fit into the socket on your extension phone, contact your dealer or nearest 

authorised service representative.

CORE

Extension phone socket

Existing extension phone (example)

Make sure you hear a "click" 
sound indicating that the 
cord is securely connected.

Attach the provided core to 
your extension telephone cord 
and then connect the cord to 
the machine.