How Does Fax Work? The 7 Things You Need To Know

Fax may have long given up the number one spot to email as the primary means of sending business documents. However, fax remains relevant today with billions of pages transmitted each year. Understanding how fax works is therefore still valuable, applicable knowledge. Here are the seven things you need to know about how modern faxing operates.

1. Fax = Scanner + Telephone + Printer

Consider fax machines as a cross between a telephone, a scanner and printer. Fax machines scan a copy of a document at the sender’s location and relay it via a phone line to the recipient’s end, where it is printed out. The fax machine sends the document as a sequence of phone signals. These are translated at the recipient’s fax machine before being printed.

For cloud-based fax services such as eFax, however, the document is sent and/or received as an email instead of a paper printout. Online fax is a cross between telephone and email.

2. Initially Used Telegraph Lines

Fax predates the telephone by about three decades. Faxes sent via traditional fax machines today are transmitted through phone lines, but that wasn’t always the case. Early faxes used telegraph lines. The faxes were sent as text messages that contained codes of short and long pulses, not too different from the Morse Code.

3. Bettered Snail Mail and Courier

Before the ubiquity of the internet and email, fax was a rapid means of sending documents when compared to courier or snail mail. The documents sent included everything from invoices meant for clients and photos sent for newspapers.

4. Unchanged Except for the Mechanics

Remarkably, faxes have largely retained the same function and design since their invention. Only the mechanics have changed.

In the 19th century, the machine’s stylus would move over a document held in position. The message on each document was written with shellac powder, a treated dry resin. When the stylus hit a blank line, the machine would remain silent. But when it ran into the shellac powder, the stylus would be raised and send out a beep.

Today’s fax machines optically scan the document instead, and there is no physical contact. They shine a light that reflects off the printed areas but not the white/blank ones.

5. The Handshake

How do the sending and receiving fax machines communicate? They have what is referred to as a handshake. It is a quick conversation where the sending machine confirms there is a fax machine to receive the document. This handshake is represented in the little dial tones you typically hear when establishing the connection.

6. Splits Page Into Numerous Squares

Fax machines will split a page into a grid of numerous squares. This is similar to the pixels on the screens of electronic gadgets. Subsequently, the fax machine reads one line of squares at a time and sends this information via beeps to the receiving fax, indicating whether the square is black or blank/white. The black and white squares are relayed as ones and zeros respectively.

As the paper is fed into the sending fax, it is being deciphered simultaneously by the receiving fax and converted back to black and white squares for the print out.

7. Best to Separate Fax Line From Phone Line

You can use the same telephone line for the fax machine and phone line in your home or office, however, best practice is to have separate lines for the two. If you use the same line for your fax as you do your phone, an incoming fax will be interrupted if someone answers the phone during transmission. That could mean starting over and/or a paper jam.

Fax Will Be Around for Decades

Many people today, especially millennials and Gen Zers, have never seen a fax machine before. And it would be understandable if they did not see the value of understanding how a fax machine operates. But whether it is a traditional fax or a cloud-based fax service, fax is bound to be around for decades.