Verify that senders are dialing the correct number and you are providing the sender with the correct fax number for your unit. If you have a second telephone number at your location or cell phone, you can test the number yourself. Dial your fax number from the second telephone number or cell phone as if you are sending a fax. If you hear ringing on the phone you are dialing from, verify if your Brother machine has a dial tone. If you hear a dial tone, this indicates there is a problem with the line or the telephone number and you will need to contact your local telephone company for assistance.