…And the answer is not 4G.
I have spent most of my career writing about telecommunications including networking, telephony, and cellular/radio. When I started in the tech writing biz cellular standards were at 2G. Next came 3G. Then came something AT&T, Sprint, and Verizon claim is 4G but isn’t.
Basically AT&T, Sprint, and Verizon are marketing the fourth generation of their networks, but those networks don’t meet the definition of 4G according to the ITU-R.
(Am I the only one who sees “ITU” and thinks “Oh, the CCITT”? Probably. Also ETSI, CEPT, ….)