CBS history started on January 27, 1927, as United Independent Broadcasters, Inc.
Even before United got started, the Columbia Phonograph Co. had become interested in the venture. The Columbia Phonograph Broadcasting System, which was to act as sales agent for United, was organized in April of 1927. United contracted to pay each of the original 16 stations $500 per week for 10 hours of radio time. Soon the Sales agent could not sell enough air time and the network was near collapse after only a few months.
The Columbia phonograph company then withdrew from the project with the sale of all capital stock which United bought and then renamed the company the Columbia Broadcasting System. William S. Paley and his family then bought the majority of CBS stock and the network began to grow. In 1995 CBS was sold to Westinghouse.
Sunday, September 18, 1927: CBS made its first network broadcast at 3 PM EST.
12/15/28: WABC New York (O&O) replaces WOR.
CBS featured its own 22 piece symphony orchestra, led by conductor Howard Barlow. Master of Ceremonies on opening day was Major J. Andrew White, who also served as Vice President of the new chain. The Opening Day programming featured a performance of "The King's Henchman", performed by a cast of performers from the Metropolitan Opera. Other programs featured classical selections by members of the New York Philharmonic, and the Philadelphia Symphony Orchestra, among others.
Columbia was known as the "Purple Network" (from the color coding on the AT&T diagrams).
Among the first networks to truly realize the power of news and to develop its use, CBS News through WWII is Frank Absher's look at the rise of network news.
Other interesting events in the CBS timeline:
January 1941, CBS started a Latin American net of 39 longwave and 25 shortwave stations in 18 countries.
1946: Flagship AM station in New York City changes calls to WCBS.
1974: CBS brought back radio drama with the CBS Radio Mystery
The archives of the CBS Radio Mystery Theater can be found here.
(All 1399 episodes are on line and are searchable.)
1975(?): along with the other networks, CBS sought the youth market with RadioRadio. These newscasts ran at :50.
November 1995: Acquired by Westinghouse.
June 1996: CBS Radio was made part of newly acquired Infinity Broadcasting, and then "spun off" as a CBS subsidiary.
December 1997: Westinghouse is officially renamed CBS Corporation.
2000: Acquired by Viacom.