"Fast-forward to 1962. Ma Bell begins using T-1s to connect its switching centers. T-1s are a digital communications link, not analog. The entire phone network goes digital. In a modern phone network, the only analog communication is between an individual house's phone line and the phone company's box."

This is misleading. The phone network used analog links (typically microwave relay) for long distance almost exclusively for many years (into the 80s) after the introduction of T1. T1 itself is not terribly well suited to very long distance links though and can only be pressed into it with repeaters every mile or so.