Advanced Mobile Phone Service, Inc. was a subsidiary of AT&T prior to the Bell System Divestiture. Abbreviated AMPS, the company was created in 1978 to build and operate the new Advanced Mobile Phone System also abbreviated AMPS. AMPS was developed by Bell Labs to replace older, severely limited radiophone services, such as IMTS. AMPS was one of the first modern cellular phone systems, which remained in operation until 2008.

Service started in Chicago on October 13, 1983 and in the Washington, DC area December 1983. After divestiture, AMPS was divided among the 7 newly created Regional Holding Companies, now known as RBOCs:

• NYNEX Mobile Communications
• Bell Atlantic Mobile Systems
• Ameritech Mobile Communications
• BellSouth Mobility
• PacTel Mobile Access
• Southwestern Bell Mobile Systems
• U S West NewVector

Evolution of Successor Companies

Through a series of mergers, acquisitions, and re-consolidation among the Baby Bells, these 7 mobile operating companies are now split between AT&T Mobility (Cingular Wireless) and Verizon Wireless. There are some discrepancies not noted on the chart due to service areas being sold off during mergers, such as Ameritech Mobile Communication's Chicago area network is now Verizon Wireless.

References

• AT&T History