How to Check Line Quality on a Fax That Won't Work

If your business’ fax machine has trouble sending or receiving faxes, a possible source of the problem is the phone line itself. Fax machines require a connection that is free from static and line noise to connect. Poor quality connections will prevent the fax machine from working properly, if at all.


Ensure that the phone line cord is connected from the “Line” jack on the rear of the fax machine to the wall jack. If the cord is not connected fully to either the fax or the wall jack or not in the “Line” jack, it may be the source of your problem. Move or connect the cord properly.


Disconnect the cord from the fax machine and plug it into the phone. Pick up the handset and listen to the dial tone. Make note of any abnormal sounds, including static, background noise, or a weak dial tone. If there is no dial tone, replace the cord with another phone line cord.


Pick up the handset again and listen for a dial tone, and make note of what you hear. If the abnormal sounds remain, the issue is the line itself. If there is still no dial tone, your phone line connection is faulty. If the sounds have disappeared, the issue was the phone line cord.


Move to the wall jack and diagnose there. Disconnect the phone line and the old wall jack, and replace with the new wall jack. Make sure you connect the wires as specified by the directions included with the wall jack itself to ensure correct operation. Replace the phone line cord and return to the phone.


Use the handset to listen to the dial tone, making note of abnormal sounds. If the problem has disappeared, the issue was the wall jack. If it remains, there is a more complex issue with the phone line. Call your telephone service provider and schedule a service appointment, noting that line noise or lack of dial tone (depending on your situation) is preventing a fax machine from working properly.


Connect the phone line cord from the wall jack to the “Line” jack on your fax machine, and test it by sending and receiving a fax. If the problem is fixed, the fax will work properly at this time.


  • Fax machines are extremely sensitive to line conditions. If the problem occurs only when sending or receiving from a specific number, the issue is more likely on that number's end and not yours. Inform the sender or receiver of the issue so he may correct it.


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