This article, and Wikipedia, and apparently everyone else, all cite the same 2001 nytimes article regarding the Committee of Ten Million to Oppose All-Number Calling. How influential were they, really, if that is the only remnant of their existence?
Here’s a New Yorker piece from 1962 mentioning them, at least: https://www.newyorker.com/magazine/1962/10/27/comment-4830
My cell phone number now is one I've had for ages and actually dates to when it mattered what area code you had for cell for cost reasons based on who you called before "favored" area codes became scarce. Think there was a Seinfeld episode based on that too.