On Apr 1, 2:41*pm, "Adam H. Kerman" wrote:

AT&T created the numbering plan in 1947, and it took effect in 1951. It's
said that they intended to number all the world's countries within it, but
I don't see how there could have possibly been sufficient numbering space..

Given the many challenges in converting the US system to universal 10
digit addressing and converting the remaining manual exchanges to
dial, I don't think they were too concerned with direct dial
international calling at that time. They still had to lay cables to
many places to replace radio for overseas calls.

Some countries couldn't be reached, by any method, until the 1970s.