An automated toll-free service was introduced by AT&T in 1966 (US intrastate) and 1967 (US interstate) as an alternative to operator-assisted collect calling and manual "Zenith" or "Enterprise" numbers. This Inward Wide Area Telephone Service (InWATS) allowed calls to be made directly from anywhere in a predefined area by dialling the prefix 1-800- and a seven-digit number.
The system was primitive by modern standards. It initially provided no support for Automatic Number Identification and no itemised record of calls, instead requiring subscribers obtain expensive fixed-rate lines which included some number of hours of inbound calling from a "band" of one or multiple US states or Canadian provinces. Early InWATS 800 calling lacked the complex routing features offered with modern toll-free service. The three digit exchange following the 800 prefix was linked to a specific destination carrier and area code; the number itself corresponded to specific telephone switching offices and trunk groups. All calls went to one central destination; there was no means to place a toll-free call to another country.
Despite its limitations (and the relatively high cost of long distance in that era), the system was adequate for the needs of large volume users such as hotel chains, airlines and hire car firms which used it to build a truly national presence.
For small regional businesses who received few long-distance calls, the original InWATS was prohibitively expensive. As a fixed-rate bulk service requiring special trunks, it was suited only to large volume users.