1967 -- 800 numbers were introduced by AT&T as what they called inward Wide Area Telecommunications Services or INWATS. Customers could receive calls originating within a relatively wide geographic area and pay for them on a "bulk" basis instead of being charged for individual calls.

1981 -- The computer revolution lead to the implementation of a first-generation system of centralized databases for processing 800-number calls according to the specific instructions in customers' records.

1984 -- With the Bell System divestiture, 800 service was required to be opened to competition. As a result, an 800 service network had to be developed that would make 800 service offerings possible for any telecommunications company.

1991 -- FCC issued order to make 800 numbers fully portable by March 4, 1993. In 1992, the FCC extended the deadline to May 1,1993.

Number Portability means that toll-free numbers are not associated with a particular carrier. Subscribers can switch to another carrier without changing their toll-free number(s), and they can choose separate carriers for specific kinds of traffic. Before number portability, toll-free subscribers were locked into their carriers. They could not change those carriers without changing their 800 numbers.

1996 - Demand for 800 numbers increased and 888 was released as 800 numbers were on the verge of being exhausted.

1998 - Demand for 888 numbers increased and 877 was released.

2000 - Demand for 877 numbers increased and 866 was released.

2008 - The SMT formed SMS/800, Inc.