AT&T created the AIO brand to compete head to head with T-Mobile in the ‘no contract’ sector of the mobile phone market. AIO selects plum, well aware of T-Mobile’s use of magenta.
Pages 6 to 13 is the discussion of steps T-Mobile took to establish rights in the color magenta as a trademark. If you have unlimited resources, this reads as the textbook for acquiring secondary meaning in a color including ‘look for’ advertising. For example, prior to ‘Black Friday’, T-Mobile ran a ‘Magenta Saturday’ sale.
Pages 13 to 18 describes AT&T’s selection of plum, to compete with magenta. Sounds like they had ‘color depletion’ problems. A lot damning stuff in their internal emails.
Some discussion of variability in the actual shade of magenta that was used at times, turns out not to be a decisive factor.
T-Mobile wins in a rout at preliminary injunction.