A major point of T-Mobiles CES presentation today was the carriers fast data speeds. CEO John Legere boldly proclaimed that his company now has the fastest 4G LTE network in the United States, claiming superiority over rivals ATT, Verizon Wireless, and Sprint. Legere said that he plans to serve ATT with a cease and desist letter over its own fastest network advertising. Im going to send a cease and desist letter to ATT telling them to stop their ads saying they are the fastest, he said. The debate over which US carrier truly has the fastest data network is a complicated one.