There are several methods that can be used to print to a fax machine, depending on the type of fax machine and its relation to the computer being used. If the fax machine is connected to the computer, then the operating system or fax driver usually will allow the unit to be used as a standard printing device, just a like a normal computer printer. In the case of a fax machine that is not attached to the computer through cables or a wireless signal, or that is in a different location altogether, it is necessary to use fax software and a faxmodem to dial the machine and send the document through the standard fax protocols. Alternately, if the fax machine is part of a remote network, then it might be possible to connect to the outside network and print to a fax machine remotely. There also are online sources that will accept digital documents or images and send them to a fax machine, removing the need for a faxmodem to print to a fax machine.
Many fax machines are part of a multi-use office machine, meaning the machine is designed to function as a standard printer as well as a fax or scanner. To print to a fax machine like this, all that is required is the proper drivers for the unit. For many operating systems, printing to a device is abstracted, so as long as the fax machine is selected in a print dialog as the output device, it can be used as a standard printer.
It can be more complex to print to a fax machine that is not designed as multi-use peripheral device. Some models, especially older models with serial connections, do not support direct printing from a computer. In these cases, the only way to print to the machine is to call it through a faxmodem.
In cases in which the computer is not connected to the fax machine, or the machine is in another area, calling the fax machine will be necessary. To print to a fax machine remotely from a computer, a faxmodem and a standard telephone line are necessary. Almost all modems have fax capabilities, meaning they are able of performing the hardware handshaking necessary to send and receive fax information. Phone lines might have problems if they are carrying a digital subscriber line (DSL) signal, or if they are Voice over Internet Protocol (VoIP) lines, which do not always use the standard dial tones necessary and might require a filter to work. Through the use of fax software, documents can be converted into images and then sent to the fax machine, which will print the image once it is received.