The Consumer Electronics Show is a giant trade expo where makers of phones and other gadgets show their latest and greatest.
In the 1980s, Northern Telecom held a press conference to show what's new. They had recently concluded an extensive market research study, and as a result, they decided to discontinue deep blue phones.
At the end of the meeting, journalists walked down the hall to a press conference hosted by AT&T. AT&T also had recently concluded an extensive market research study, and as a result, they decided to produce phones in a blue color nearly identical to what their competitor had decided to drop.
The AT&T/Bell System ad linked below shows the same type of blue from the 1950s.
GTE had a similar blue in the late 1940s.
Panasonic introduced a similar blue phone color in 2007.