Ameritech Corporation (and before that American Information Technologies Corporation) was a U.S. telecommunications company that arose out of the 1984 AT&T divestiture. Ameritech was one of the seven Regional Bell Operating Companies that was created following the breakup of the Bell System. Ameritech was acquired by SBC Communications in 1999 which subsequently acquired AT&T Corporation in 2006, becoming the present-day AT&T Inc.
Ameritech was created as a holding company; under its umbrella were:
- Illinois Bell Telephone Company
- Indiana Bell Telephone Company, Inc.
- Michigan Bell Telephone Company
- Ohio Bell Telephone Company
- Wisconsin Bell, Inc.
For Ameritech's first nine years, it maintained these Bell brands inherited from the Bell System—though public displays of the Bell companies' names were often captioned "An Ameritech Company". In January 1993, Ameritech officially retired the Bell brands and marketed itself with solely the Ameritech name across all five states in its territory. It added "d/b/a Ameritech (state)" to the names of its Bells to communicate brand unity.
Ameritech also owned Ameritech Cellular, a wireless company that operated cellular networks in many of the major cities of these states. Ameritech Cellular was previously called Ameritech Mobile Communications.
Prior to its merger with SBC Communications, Ameritech's corporate headquarters were in a leased space above the Chicago Mercantile Exchange on floors 34 through 39 of 30 S Wacker Dr, Chicago IL. Further corporate offices were located at 225 W Randolph St, Chicago IL (formerly "The Illinois Bell Building") and 2000 W. Ameritech Center Drive, Hoffman Estates, IL ("The Ameritech Center"). It was traded on the NYSE under the "AIT" symbol.
In May 1998, Ameritech announced its intent to merge with SBC Communications. This brought great concern to Federal and state regulators, who in turn didn't approve the merger until SBC and Ameritech agreed to several conditions  to ensure adequate competition. Most notably, regulators required:
- that the merged company offer local phone service in thirty markets outside of its home territory within thirty months of the merger (i.e. by April 2002) or pay a $1.18B penalty
- and that Ameritech Cellular assets in Chicago be sold to GTE. Since SBC already had a majority stake in a large mobile provider (Cellular One), the merged company, if it were to operate Ameritech Cellular and Cellular One both in the same market, would have wielded too much market power.
On January 15, 2003, SBC Communications changed its d/b/a names, and then changed the legal name of Ameritech Corp. to SBC Teleholdings, Inc., and would begin doing business as SBC Midwest. On January 15, 2006, AT&T changed its d/b/a names, and Ameritech was again renamed, becoming AT&T Teleholdings, Inc. and began doing business as AT&T Midwest.
Several Ameritech subsidiaries remain legally named "Ameritech", such as Ameritech Advanced Services; however, they do business as "AT&T Advanced Solutions".
|||American Information Technologies Corp.
Ameritech began in 1984 as American Information Technologies. Ameritech only displays its corporate logo for corporate purposes, or denoting a Bell Operating Company "An Ameritech Company".
In 1993, Ameritech chooses to do business as one "Ameritech", and drops the names of its Bells in advertising, and comes with a new logo. This logo remains until 2001.
|||SBC Global Network
In 1999, SBC acquires Ameritech. Shortly after, SBC begins attaching "SBC Global Network" to the ends of its subsidiary logos.
In 2001, SBC proceeds to "unify" its companies by adding the "SBC" corporate logo to the operating company logos, and begins advertising Ameritech as "SBC Ameritech".
|||SBC Teleholdings, Inc.
In 2002, SBC drops the names of all of its Bells in favor of advertising as one "SBC". On January 1, 2003, SBC changes its d/b/a names, resulting in "d/b/a SBC (name of state or region)" to the official names of its companies. Ameritech's legal name is changed to SBC Teleholdings, and does business as "SBC Midwest", and its operating companies do business as "SBC Illinois", "SBC Indiana", "SBC Michigan", "SBC Ohio", and "SBC Wisconsin".
|AT&T Teleholdings, Inc.
In 2005, SBC completed its acquisition of AT&T Corp., forming AT&T, Inc. AT&T changes the d/b/a names of its Bell Operating Companies on January 1, 2006, resulting in "AT&T Midwest" and "AT&T Illinois", "AT&T Indiana", "AT&T Michigan", "AT&T Ohio", and "AT&T Wisconsin".
- ^ "AT&T Teleholdings, Inc.: Private Company Information - BusinessWeek". http://investing.businessweek.com/research/stocks/private/snapshot.asp?privcapId=169415. Retrieved 2008-09-08.
- Bell System Memorial's RBOC page
- FCC APPROVES SBC-AMERITECH MERGER SUBJECT TO COMPETITION-ENHANCING CONDITIONS (FCC decree allowing merger)