World population by late 1990s was 6 billion. Landline audio phone calls were reliable with fixed guaranteed bandwidth, albeit expensive. Today there are more people, but has there been a linear increase in 1:1 calls? More bridge/group/conferencing calls, yes.
But not in the 2nd/3rd world or in rural areas or poorer areas in the first. I would suggest that the ubiquity was in the wealthiest sections of the 1st world, not the western world.
