T-Mobile will stop advertising its network is faster than Verizon's because its claim is unsupported.

The decision by T-Mobile was made on the heels of the National Advertising Division (NAD) "recommending" it stop its advertising techniques. The NAD is an advertising regulatory body that aims to settle disputes without resorting to legal battles.

NAD "recommended T-Mobile discontinue claims that it has the fastest 4G LTE network" because it does not have enough substantial evidence to support the claim. T-Mobile gathered crowdsourced speed tests from Ookla and Open Signal. Verizon and other major carriers used RootMetrics to measure the speeds of their networks.

Verizon filed a challenge against T-Mobile's claims through the NAD arguing customers who tested the speed of the network were likely over their data cap, likely contributing to slower speeds. Both Verizon and T-Mobile use the practice of slowing down speeds after users hit a cap, resulting in deprioritized speeds.

Verizon also tried to shut down T-Mobile's claim that its network was a big as Verizon's, but the NAD sided with T-Mobile partially because the carrier covers 99.7-percent of Americans covered by Verizon. However, T-Mobile also acknowledged it does not cover the same 99.7-percent geographic area Verizon covers.

Oddly enough, NAD previously greenlit T-Mobile's crowdsourcing practice back in 2015, but advised it not to use deceptive tactics. T-Mobile didn't comply, and thus NAD sided with Verizon.

T-Mobile agreed with NAD's decision and will stop advertisements that market that message. That's a big blow to its marketing campaign that found a great hook when talking down Verizon's speed and reach.

T-Mobile later provided a response to the story, saying it is still the fastest LTE network.

"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," stated Janice V. Kapner, SVP of Corporate Communications at T-Mobile. "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!"

T-Mobile did not elaborate on the tests it will go through to confirm that it is still the fastest LTE network. For now, NAD's recommendation still stands that "T-Mobile discontinue claims that it has the fastest 4G LTE network."

Updated: The story was updated to include T-Mobile's statement.