AT&T started rebranding their "System 75" and "System 85" systems to "Definity 75/85" in 1989 as mainstream commercial campaigns appeared on primetime TV. In April 1990, AT&T rebranded these systems with the two versions of System 75 as "Generic 1" and "Generic 3" and the "System 85" as "Generic 2", By 1995, AT&T was migrating their customers away from the 20 year old Dinension band-aid'd up system to the more scalable Generic 3 that's roots go to the original System 75. You can see more in the migration doc. In 2002, Avaya decided to dicontinue the brand meaning "definitive solutions for an infinite amount of possibilities" to a really clunky name called MultiVantage 1.0, but then corse corrected to Communication Manager 2.0 to then be renamed "Aura" by the end of the decade. It should be be noted that in Aura 8x, it's really under the hood as the 18th version of the orignal System 75 code, and really dropped the most left hand number in marketing during that MultiVantage release. Collectors just call it "the Definity" which says something.