After filing a lawsuit against AT&T and the big blue carrier's 5G E branding last month, Sprint continued going after AT&T for 5G E this past weekend.

Sprint took out a full-page ad in the Sunday edition of The New York Times to call out AT&T for "deceiving consumers into believing that their existing 4G LTE network operates on a much-coveted and highly anticipated 5G network." In its letter, Sprint calls AT&T's 5G Evolution "fake 5G" and explains that it's suing AT&T over the 5G E branding, which Sprint describes as a "false and deceptive marketing campaign."

Sprint goes on to say that it played a role in developing 5G standards and that by this summer, it'll launch 5G service in nine metro areas. Sprint recently confirmed that Chicago, Atlanta, Dallas, and Kansas City will get its mobile 5G coverage first, followed by rollouts in Houston, Los Angeles, New York City, Phoenix, and Washington D.C. in the first half of 2019.

AT&T's 5G Evolution network uses advanced 4G LTE technologies like 3-way carrier aggregation, 256 QAM, and 4x4 MIMO to boost download speeds. The carrier has already begun rolling out its 5G E indicator to Android phones, and recent iOS 12.2 betas have shown that iPhones will get the 5G E branding, too. AT&T has caught a lot of criticism for the 5G E branding, but AT&T has defended 5G E by saying that it's trying to "let [customers] know that there is an enhanced experience in their market."

AT&T has deployed true 5G coverage in parts of 12 U.S. cities, but the only device that can access it is the Netgear Nighthawk 5G Mobile Hotspot.

You can read Sprint's full letter that appeared in The New York Times right here.