AT&T

Background
The original AT&T Corporation was founded in March 3, 1885 by Alexander Graham Bell, Gardiner Greene Hubbard and Thomas Sanders, initially as one of the subsidiaries of the American Bell Telephone Company. It soon became the new parent company after acquiring the latter company's assets on December 30, 1899. Since then, the company (along with its subsidiaries) had held a monopoly called the Bell System, which was split up by 1983.

1st Logo (1966-1969)
Logo: On a blue background, we see the Bell System of the time with the text "AT&T" next to it. Below it is "and Associated Companies". A copyright notice is seen below.

Variants:
 * On The Incredible Machine, the background is black, and the logo is paired with the Owen Murphy Productions logo.

Technique: None.

Availability: Extinct. Seen at the end of shows/films like The Incredible Machine.

2nd Logo (1982-1984)
Logo: Just the logo of the time in dark blue on a blue background, alongside the copyright year below it.

Technique: None.

Music/Sounds: The closing theme of the show.

Availability: Presumably seen on AT&T corporate videos during the government-mandated transitionary period in which the Bell System worked with the government on an acceptable breakup plan, and also appears at the end of 1983-1984 editions of The MacNeil/Lehrer NewsHour.

3rd Logo (January 9, 1984-1991)
Logo:
 * On a black background, we see blue triangular prisms flying forward forming the AT&T sphere logo. As it rotates a bit, we see "AT&T" slide up and the logo turns 2D.
 * Similar to the above; we see a front view of the prisms flying from the left to form the AT&T sphere logo. "AT&T" fades in below. The logo turns 2D.

Variant: Sometimes, the logo would be still, and the copyright year appears below it.

Trivia: This logo was designed by Saul Bass, who also did the 1969 logo for the Bell System (which AT&T owned until 1983), and the Warner Bros. "Big W" logo.

Technique: CGI.

Music/Sounds: Either a warbly synth bass, followed by five synthesized notes and four synth-piano notes or no music at all.

Music/Sounds Variant: One variant had a different synth theme.

Availability: Seen on corporate videos from AT&T. This animation was also seen on MacNeil/Lehrer programs on PBS which had AT&T as their corporate sponsor, including The MacNeil/Lehrer NewsHour and My Heart, Your Heart.

Copyright stamps

 * 1968: Copyright © by American Telephone and Telegraph Company
 * 1982-1991: Copyright © by AT&T