If you have recently installed Fax machine and want to Test Fax Machine for its functionality, you have to send one-page black and white text fax to a phone number. And also ensure that the fax machine is plugged-in into the line appropriately. Once your fax is received by the HP Test Fax Service, it proves that you can both send and receive a fax. But in case, the text fax fails to send and receive, then make sure your complete 10-digit fax number is added in the fax header and that matches the telephone number connected to the fax.