But why would Japan run out of phone numbers with the population shrinking? While of course IoT devices need to be addressable, that's more of an IPv6 problem

But why would Japan run out of phone numbers with the population shrinking? While of course IoT devices need to be addressable, that's more of an IPv6 problem than a phone number problem.... right? A person might have a few numbers, at most - and a flat if not shrinking number (I used to have home, work, cell; but have only had cell for a while now)