You still had telephone operators 10 or 20 years ago? The earliest telephone backbones that didn't require operators anymore are from the 1920s. Operators were

You still had telephone operators 10 or 20 years ago? The earliest telephone backbones that didn't require operators anymore are from the 1920s. Operators were still used for international calls, but definitely not after ~1990. Source: There is a telecommunications museum across the street from my workplace.