The big four cellphone carriers are in a never ending game of cat and mouse over who has the best network. With all of the different claims surrounding speed, reliability, and coverage, it can get confusing as to what is and isn't true in these ads. The National Advertising Division is a telecom watchdog group aimed at resolving conflicts and keeping carriers honest in these situations. They have recently warned T-Mobile not to advertise that they have the country's fastest LTE network, but T-Mobile says they will continue to make the claim and have new data to back it up.

Verizon originally filed a complaint with the NAD since they believed the 3rd party data that T-Mobile used was skewed. According to Verizon, the Ookla and OpenSignal data were more likely to sample T-Mobile unlimited customers and therefore could not be used to backup the claim. The data was captured right after Verizon reintroduced their unlimited plans and they believe this invalidates the findings.

The NAD also recommended that T-Mobile modify the claim that they covered 99.7% of Verizon customers to make it clear that this measurement was by population and not geographic area.

T-Mobile Senior VP of corporate communications Janice Kapner issued a statement saying:

"On the fastest LTE network challenge, NAD ruled that the one month of crowd-sourced data we submitted (when Verizon launched their unlimited plan) could not be used."

"NAD previously recognized third-party crowd-sourced data as a way to look at network performance, so we looked at the latest results, and verified what we already knew! T-Mobile is still the fastest LTE network and we’ll continue to let consumers know that!"

It's unclear where the data is from or how it differs from the Ookla data, but they think it is enough to resume making these advertisement claims.