800 is the oldest of all the area codes that are associated with toll-free phone numbers. 800 numbers can be linked to direct lines or can function as a virtual number. They can be arbitrary digits or vanity numbers that are directly associated with a company's branding strategy. Although 888, 877, 866, 855 and 844 were released by the FCC for the same purpose, the 800 area code is still the most recognizable and most widely associated with toll-free calling.
The first toll-free number was released by AT&T in 1967. It began with the area code 800, and was designed to offer customers an easy way to call a business without incurring a charge. Prior to that, customers had to call businesses collect, and could not be connected until the company agreed to pay for the call. Toll-free 800 numbers gave customers the means to call businesses directly, without cost or hassle, to place orders, inquire about shipments, seek customer service, register complaints or ask questions. The system was immediately popular, with 7 million calls placed to 800 numbers in the first year alone.
Some businesses choose not to have their 800 number linked to a fixed line. Instead, their toll-free number functions as a virtual number. Virtual numbers route incoming calls through a forwarding service to any predetermined line or lines chosen by the number's owner. Virtual numbers remove the need for physical call centers, which is especially important for international businesses. When a call is placed to a virtual 800 number, it can be forwarded to a fixed line, a mobile line, a messaging service or a series of secondary numbers if the primary number is occupied or unmanned.
800 numbers — including vanity numbers — can be used with essentially any phone system. Aside from virtual numbers, 800 numbers can be used for mobile lines or fixed lines on the public switched telephone network, or PTSN. The number can be the caller's gateway to voice over Internet protocol — or VoIP — networks, whether that network is built on a private branch exchange — or PBX — system, or a session initiation protocol — or SIP — system.