Email Fax

Email Fax or otherwise known as Internet Fax uses the internet to receive and send faxes.

Email fax (or "online faxing") is a general term which refers to sending a document facsimile using the Internet, rather than using only phone networks (traditional faxing).

Depending on the specific method/implementation (see below), advantages of using the internet can include

no extra telephone line required for the fax
paperless communication, integrated with email fax
send and receive multiple faxes simultaneously
reduction in phone costs
ability to receive and send faxes from any location that has Internet access

Traditional Fax

The traditional method for sending faxes over phone lines (PSTN)

Fax machine → Phone line → Fax machine

A fax machine is an electronic instrument composed of a scanner, a modem, and a printer. It transmits data in the form of pulses via a telephone line to a recipient, usually another fax machine, which then transforms these impulses into images, and prints them on paper.

The traditional method requires a phone line, and only one fax can be connected to send or receive at a time.

Computer-Based Faxing

As modems came into wider use with personal computers, the computer was used to send faxes directly. Instead of first printing a hard copy to be then sent via fax machine, a document could now be printed directly to the software fax, then sent via the computer's modem. Receiving faxes was accomplished similarly.

Computer → Phone line → Fax machine
Fax Machine → Phone line → Computer

A disadvantage of receiving faxes this way is that the computer has to be turned on and running the fax software to receive any faxes.

Internet Fax Servers/Gateways

The Internet has enabled development of several other methods of sending and receiving a fax. The more common method is an extension of computer-based faxing, and involves using a fax server/gateway to the Internet to convert between faxes and emails. It is often referred to as "fax to mail" or "mail to fax". This technology is more and more replacing the traditional fax machine because it offers the advantage of dispensing with the machine as well as the additional telephone line.

Fax Using Voice over IP(VoIP)

Making phone calls over the Internet (Voice over Internet Protocol, or VoIP) has become increasingly popular. Compressing fax signals is different from compressing voice signals, so a new standard (T.38) has been created for this. If the VoIP adapter and gateway are T.38 compliant, most fax machines can simply be plugged into the VoIP adapter instead of a regular phone line.

Fax machine → VoIP adapter → VoIP gateway → Phone line → Fax machine (or vice versa)

As with regular faxes, only one fax can be sent or received at a time.

Fax Using Email