The modern telephone system is, as I understand it, basically a parallel Internet with different protocols and equipment specifically geared toward audio. In some cases, it probably goes over the actual Internet. Back in the day, though, every telephone conversation needed a dedicated piece of copper from one end to the other. That piece of copper was assembled bit by bit through switchboards. That's also why long distance calls were so expensive: if you only had 100 copper lines between the US and Europe, then you could only have 100 simultaneous calls between the US and Europe. Today, if you have 100 fiber lines between the US and Europe, that might let you have 100000 simultaneous calls between the two regions.