AT&T

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 light 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: The flying, and the sliding. It's all in early 80s 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.