There are several reasons this message would appear when sending a fax.
If the fax number you are dialing does not answer, this message will appear. Verify you have the correct fax number and try again.
Verify the telephone line cord is connected from the socket on the FAX/MFC labeled LINE directly to the WALL socket. Disconnect and reconnect to ensure the connection is secure and solid.
If the receiving unit is busy, the sending unit will automatically redial the number within 5 minutes. The sending unit will attempt to redial up to three times at five minutes intervals. If the unit is still busy, the sending unit will display "No Response/ Busy" and print out a report with the same message.
Anytime you want to make a second call to the last number dialed, press Redial/Pause and then Start.