I know how it works. You are solely considering the latest generation of equipment. There is still a lot of analogue kit (crossbar switches/relays) out there a

I know how it works. You are solely considering the latest generation of equipment. There is still a lot of analogue kit (crossbar switches/relays) out there across the globe. There are even small pockets of it in the UK. POTS is definitely not irrelevant if you throw away the notion that everyone is not an iPhone wielding hipster. However you miss the point. The existing abstraction of "phone number" is so universally powerful that the underlying implementation, regardless of what encapsulation and routing algorithms used is effectively a logical replacement for the analogue switching. It's like "virual analogue synthesizers" which are replacements for synthesizers. The abstraction was so powerful, the new technology emulates the old.