The first point to realise is that bandwidth is virtually infinite, and that with the current technology bandwidth over distance is virtually free in large aggregated amounts. Bandwidth has real cost and scarcity only when it needs to be switched or processed or handled in small amounts. Out in the wide world it only has scarcity because governments regulate, and monopolies monopolise, and oligopolies do whatever oligopolies do. Any scarcity we have is artificially contrived to keep prices high. Let's look at fibre cables, and use my favourite example - the cable links between Melbourne and Sydney.
Telecom has four fibres joining the two cities, two old and two new ones.
Their first cable runs down the centre via Canberra, and the other wanders around the coast via Wollongong. There's satellite links and microwave backups also, but we won't count these - their contribution is trivial. I keep stressing PCM here, because the old techniques of coding voice are only being used today by carriers when they have enormous excess capacity. It then doesn't pay them to junk the old reliable standard and use half-rate codecs. Optus, for instance, runs PCM and it only bothers to fire up one of its fibre-pair in each cable.