Most Fax Machines Connect to Telephone Lines
A fax machine works by scanning a document into a digital image, modulating the image into sound, connecting to another fax machine across a telephone network and sending the modulated data as machine-readable sound. Because this process requires a connection to the public-switched telephone network (PSTN), a fax machine must have some connection to a telephone line. This connection is generally accomplished by plugging a dedicated telephone line into the fax machine.
Fax Machines May Share the Line
The fax machine does not need any special services on the fax line; the sound produced by the machine can be sent across any telephone connection. Because a dedicated fax line can be a considerable expense for a small business, a slew of items that allow a fax machine to share an existing (voice) telephone line have entered the market. One such item is a telephone ring director (available from providers like ablecomm.com and hellodirect.com); this device works with a subscription to a "distinctive ring" service offered by your local telephone company. When a caller dials your regular telephone number, the line rings in a traditional pattern and the call is sent to your telephone. When a caller dials your secondary--presumably, your fax--number, the telephone company sends a special ring to your telephone line indicating the call type. The ring director device recognizes this special ring and routes the call directly to the fax machine. Since you control when you want to send a fax, outgoing faxes do not interfere with normal telephone conversations.
Some fax machines with exceptional error-handling capabilities or high-quality telephone connections may work well with telephone service alternatives such as Voice Over IP (VoIP) service. This service allows the fax machine to connect to the public-switched telephone network through a regular Internet connection, eliminating the need for a traditional phone line. VOIP service ranges in price from a low annual fee to a monthly rate plan, however, and the unregulated quality of the service may occasionally interfere with fax services.
Some users choose to bypass the expense of a fax machine and telephone line altogether, opting for one of many online fax services. Companies like FaxDigits.com and eFax.com offer the ability to send documents or pictures directly from your computer and an online fax "inbox" where you can receive faxes. These services range in price from free to a nominal monthly charge.