IP fax

Internet fax, e-fax, or online fax is the use of the internet and to send a fax (facsimile), rather than using a standard telephone connection and a fax machine. A distinguishing feature of Internet fax, compared to other Internet communications such as email, is the ability to exchange fax messages with traditional telephone-based fax machines.

Fax has no technical advantage over other means of sending information over the Internet, using technologies such as email, scanner, and graphics file formats; however, it is extremely simple to use: put the documents to be faxed in a hopper, dial a phone number, and press a button. Fax continues to be used over the telephone network at locations without computer and Internet facilities; and sometimes a fax of a document with a person's handwritten signature is a requirement for legal reasons. Computer fax over the Internet allows fax communication without an actual fax machine at either or both ends.

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

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 pulses 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. The phone connection must not be a packet-based system in which delays can occur—a VoIP connection will not work well without special precautions (T.38-compliant equipment at both ends).

Internet fax achieves a dramatic reduction in communication costs especially when long faxes are frequently exchanged with overseas or distant offices.

Since there is no telephone connection charge when sending a fax over the Internet, the cost of sending faxes is covered entirely by the fixed line Internet connection fee. The recipient can either use a fax machine or an internet fax service to be able to receive faxes sent via the internet fax method.

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Wikipedia