I’m not sure that was true in 1990 in the United States. In the old analog networks, the central offices could route calls locally among phone numbers that shared the same central office, which was basically any number that had the same first 3 digits of the 7 digit number under the North American Numbering Plan. At least for the suburban neighborhood I grew up in, in the 80’s, the neighborhood pizza places had the same central office code as my home phone number.
It wasn’t until the rise of digital switching that the phone number itself got decoupled from the actual network topography, and things like number portability became possible. But in the analog systems they wanted to minimize switching where possible, so “local” calls weren’t all equally local.
I’m not sure that was true in 1990 in the United States. In the old analog networks, the central offices could route calls locally among phone numbers that shared the same central office, which was basically any number that had the same first 3 digits of the 7 digit number under the North American Numbering Plan. At least for the suburban neighborhood I grew up in, in the 80’s, the neighborhood pizza places had the same central office code as my home phone number.
It wasn’t until the rise of digital switching that the phone number itself got decoupled from the actual network topography, and things like number portability became possible. But in the analog systems they wanted to minimize switching where possible, so “local” calls weren’t all equally local.