Internet fax

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Internet fax uses the internet to receive and send faxes.

Traditional faxing involves sending a scanned copy of a document (a facsimile) from one fax machine to another, over the phone network. Internet faxing (or "online faxing") is a general term which can refer to one of several methods of achieving this over the Internet - with a goal of both reduced costs and increased functionality over 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
send and receive multiple faxes simultaneously
reduction in phone costs

Note that depending on which method is used, suitable equipment and/or the use of a gateway is required (see below).

1 Traditional fax
2 Computer based faxing
3 Internet Fax servers/gateways
4 Fax using Voice over IP
5 Fax using email
6 See also

[edit] Traditional fax

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

Fax machine → Phoneline → 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 sent or received at a time.

[edit] Computer based faxing

As modems became common, some computers were used to send faxes directly. Instead of printing a document, and then putting it in a fax machine - computer software allowed users to print directly to the software fax, and then send the fax using the modem. Receiving faxes was accomplished similarly.

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

Disadvantages of receiving faxes this way are that the computer has to be turned on and running the fax software to receive any faxes.
Note: This is not Internet faxing as the Internet is not used.

[edit] 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.

Reception:

Fax machine → Phone line → Fax gateway → email message (over Internet) → computer email account

A fax is sent via the Public Switched Telephone Network (PSTN) on the fax server, which receives the fax and convertes it into PDF or TIFF format, according to the instructions of the user. The fax is then transmitted to the Web server which posts it in the Web interface on the account of the subscriber, who is alerted of the reception by an email containing the fax in an attached file and sometimes by a message on his mobile phone.

Sending:

Computer → Internet → Fax gateway → Phone line → Fax machine

From his/her computer, in the supplier Web site, the user chooses the document s/he wants to send and the fax number of the recipient. When sending, the document is usually converted to PDF format and sent by the Web server to the fax server, which then transmits it to the recipient fax machine via the Standard Telephone Network. Then the user receives a confirmation that the sending was carried out, in his/her web interface and/or by email.

An Internet fax service allows one to send faxes from a computer via an Internet connection, thanks to a Web interface usually available on the supplier's Web site. This technology has many advantages:

No fax machine → no maintenance, no paper, toner expenditure, possible repairs, etc.
Mobility → All actions are done on the Web interface; the service is thus available from any computer connected to Internet, everywhere in the world.
Confidentiality → The faxes are received directly on the account of the user; he is the only one who can access it. The received faxes are not likely to be lost any more or read by the wrong people.
No installation of software or hardware → All actions are done on the Web interface of the supplier, on the account of the user.
No telephone subscription for an additional line dedicated to the fax.
Many faxes can be sent or received simultaneously, and faxes can be received while the computer is switched off.

[edit] Fax using Voice over IP

Making phone calls over the Internet (Voice over Internet Protocol, or VoIP) has become increasingly popular. Compressing fax signals is different than 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.

[edit] Fax using email

While the needs of computer-to-fax communications are well covered, the simplicity of quickly faxing a handwritten document combined with the advantages of email are not.

"iFax" (T.37) was designed for fax machines to directly communicate via email. Faxes are sent as e-mail attachments in a TIFF or PDF format.

Fax machine → email message (over Internet) → computer email account
Fax machine → email message (over Internet) → Fax machine (using email address)

A new fax machine (supporting iFax/T.37) is required, as well as a known email address for the sending and receiving machines. This has limited the standard's use, though a system for looking up a fax's email address based on its phone number is under development [1].

To work with existing fax machines, all iFax machines support standard faxing (requiring a regular phone line). Alternatively, an iFax can be used in conjunction with a fax gateway.