How much of modern POTS is reliant on VOIP? In Australia at least, POTS has been decommissioned entirely, but even where it's still running, I'm wondering where IP takes over?

I am guessing that most POTS is VOIP now, except for the few places with existing copper infrastructure that has not been decommissioned yet.

This person has a POTS line in their current location, and a modem, and the software stack to use it, and Instagram has POTS lines and modems and software that connect to their networks? Wow. How well do Instagram and their internal applications work over 56K?

He called on his mobile phone. As a result it was a voice-only conversation, no video.

They could have dialed in by their own cell phone though

I read that as POTUS at first and paused for a minute

What is POTS?

Plain old telephone service https://en.wikipedia.org/wiki/Plain_old_telephone_service

Plain old telephone system. Aka a phone.

Plain Old Telephone System