T-Mobile on Wednesday agreed to pay a sum of $48 million to settle an FCC investigation into its handling of "unlimited" data plans.

The FCC in March 2015 opened an investigation into the carrier's practice of de-prioritizing unlimited data plan customers during times of network "contention." It found that during times of contention, the top three percent of T-Mobile and MetroPCS data users were indeed being de-prioritized.

When this "top three percent" policy is enforced, a network algorithm controls the heavy data users' network access and the speed of their data connection.

Interestingly enough, the FCC wasn't bent out of shape over the practice but rather, T-Mobile's lack of transparency that it was taking place. Prior to June 2015, the FCC says the carrier's public disclosures about de-prioritization were not sufficient to fully inform customers about what would take place when the policy is enforced.

The FCC added that it received hundreds of complaints during its investigation from customers that were unhappy with the fact that they weren't subject to the truly unlimited data they had signed up for.

As per the settlement, T-Mobile has agreed to update its disclosures for plans regarding its de-prioritization policy and be more transparent about it with regard to consumer-facing advertising and marketing material.

What's more, T-Mobile will pay a civil penalty of $7.5 million, spend at least $5 million to help bridge the "homework gap" in low-income school districts and set aside at least $33.5 million for consumer benefits for current T-Mobile and MetroPCS unlimited data plan customers. Benefits will include a discount of up to 20 percent (up to $20) off the regular price of any in-stock accessory.

Additionally, unlimited data customers that subscribe to a mobile Internet data plan will automatically receive a free upgrade of 4GB of additional data.

Image courtesy Malarie Kokey, Digital Trends