Earlier quoted context omitted.
That's not accurate. AT&T dominated telecommunications for decades before the transistor. Many of Bell Labs great scientific inventions predate the transistor, such as information theory.
Sure, but the transistor ushered in the long-distance era and helped AT&T establish their monopoly (and their eventual breakup). Regional telephone services were already beginning to drive down costs in local markets.
They had direct-dial long-distance by 1951, using relays and tubes.
The transistor started making a difference in telephony with the release of the 1ESS switch in 1965. But transistors were a commodity by then.