Template:Evolution of AT&T
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| 1885 | American Telephone and Telegraph corporation is founded as the long-distance subsidiary of the Bell Telephone Company. |
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| 1899 | Massachusetts law leads to AT&T merging with Bell Telephone and becoming the successor company. |
| 1913 | The Kingsbury Commitment allows AT&T to legally continue its growing monopoly over telecommunications |
| 1915 | AT&T's development of the first transcontinental phone call leads to nationwide telephone networks |
| 1925 | Bell Laboratories is formed to oversee research and development efforts |
| 1950s | Over the years, AT&T becomes the United States dominant telephone business in America and is among the largest American corporations |
| 1974 | The U.S. Department of Justice sues AT&T for violating antitrust and seeks a full divestiture of the Bell System |
| 1982 | AT&T reaches a settlement to separate the Bell System into seven regional companies and holds on to its long lines and technologies divisions |
| 1990s | After several acquisitions, AT&T briefly becomes the largest American cable and broadband internet provider |
| 2002 | Heavy debt leads to AT&T spinning off its broadband and wireless services units into public companies |
| 2005 | SBC Communications acquires the original AT&T Corporation and reincorporates as AT&T Inc. |
| 2015 | DirecTV is acquired, briefly making AT&T the largest U.S. Pay-TV operator |
| 2018 | AT&T acquires Time Warner, becoming a major player in entertainment, and renames the company to WarnerMedia |
| 2022 | WarnerMedia is spun off from AT&T and then merges with Discovery, Inc. to establish Warner Bros. Discovery |
| 2025 | AT&T's majority stake in DirecTV is sold to private equity firm TPG Capital |
| 2026 | Lumen Technologies fiber networks are sold to AT&T, and AT&T strengthens its leading coverage of U.S. fiber internet |