On 9/23/1962, the New York Times had a very detailed article on the
> conversion to All Number Calling (ANC), consumer opposition and
> frustration to ANC, and future prospects of telephone systems. This
> may answer some of your questions of how the system evolved. The NYT
> is available on microfilm or CDROM in many large libraries.
It's also available to Times Select subscribers on the internet.
Interesting how the article discusses:
Data transmission at an "amazing" 2000 bits per second. AT&T had predicted that 2L+5N dialing would have reached capacity by 1970. ANC would resolve capacity issues until 2000 (only 5 years off). The reason behind not going to a 3L+5N dialing plan. The magic Electronic Central Office of the future, with its 23,000 neon-filled tubes, that would allow (what we know now as) 3-way calling, speed dialing, call forwarding, and home intercom.