Mobile carriers like to play fast and loose with the word "unlimited" when it comes to data plans. They're often technically unlimited, but only fast enough to be useful until you hit a certain barrier. MVNOs operated by TracFone including Net10 and Straight Talk were a little more shady than most, and that led to today's FTC announcement of a $40 million fine against the company.
The FTC filed a complaint against TracFone after receiving complaints from a fair number of customers whose data had been throttled or blocked entirely after they hit a murky monthly cap. TracFone-owned entities didn't disclose the limits up front, but most users were throttled at 1-3GB and they were cut off at 4-5GB. Some customers also had their lines terminated by TracFone for hitting the unstated limit too often.
The multi-million dollar fine puts an end to the case and provides former and current customers some restitution. Anyone who was a TracFone customer before this month can file a refund claim. TracFone is also required to change its advertising and explain what the data caps are when consumers sign up for a plan. This action strengthens the FTC's case against AT&T for selling "unlimited" plans that aren't really unlimited. That case is still ongoing.