https://phys.org/news/2019-02-sprint-sues-att-company-5g.html

Since late last year, AT&T has been touting its upgraded 4G LTE network as 5G E in TV ads, ramping up the running of the spots in 2019.

AT&T, Sprint alleges, "has sought to gain an unfair advantage in the race to 5G by embarking on a nationwide advertising campaign to deceive consumers into believing that its existing 4G LTE Advanced network is now a 5G network."