Why do telcos. insist on doing overlays? They sound like such a pain. They are contrary to everything the Bell System desired in the PSTN.
I am fortunate enough to live in the 262 area code, which was a split from 414 about 25 or so years ago. If you look in the old phone books, the older prefixes, such as (262) 542-xxxx were once (414) 542-xxxx. The numbers themselves did not change, only the area code, so there was absolutely no impact when the 262 area code since the area code you are in generally does not matter to you.
Why not split area codes instead of overlay them? Everyone can keep their number and the area is still split. Geographically, area codes fail to have meaning if they are overlaid and, furthermore, they require 10 digit dialing, which is a huge pain from a rotary phone! ________________________________