Epson WorkForce WF-2930 Wireless All-in-One Color Inkjet Printer - Manual (Page 159)

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2. If you are connecting a telephone or answering machine to your product using a second phone
cable, remove the cap from the
EXT port on your product.
Note: If your telephone has a fax function, disable the fax function before connecting it. If you are not
able to completely disable the fax function on your telephone, you may not be able to use it as an
external telephone.