When T-Mobile announced its new "uncarrier" plans, a lot of mobile phone industry observers shrugged.

T-Mobile was eliminating the industry-standard two-year contract, but it was also eliminating the device subsidies to which US consumers have long grown accustomed. For example, an iPhone 5 that would cost you $199 with a 24-month commitment on AT&T or Verizon could now be had from T-Mobile for $579 with no contract. Or, T-Mobile would hand you the phone for a $99 downpayment plus $20 a month for 24 months—if you cancelled your service, you'd be responsible for a lump-sum payoff on the balance of your phone.

The new T-Mobile plans typically came out to be about $20 a month or so cheaper than AT&T or Verizon, so it was kind of a wash, with the $20 monthly phone payment largely offsetting the typical savings on the new "uncarrier" plans. And the lump-sum payment due on canceling your service was functionally no different from early termination fees the other carriers still charge.

That last detail apparently escaped the attention of a lot of new T-Mobile customers:

Washington State Attorney General Bob Ferguson has ordered T-Mobile to correct deceptive advertising that promised consumers no annual contracts while carrying hidden charges for early termination of phone plans.

Today, the Attorney General's Office filed a court order signed by T-Mobile and effective nationwide that will ensure the company clearly communicates the limitations of its new “no-contract” wireless service plans and allows customers duped by the deceptive ads to exit their contracts with no penalty.

“As Attorney General, my job is to defend consumers, ensure truth in advertising, and make sure all businesses are playing by the rules,” Ferguson said. “My office identified that T-Mobile was failing to disclose a critical component of their new plan to consumers, and we acted quickly to stop this practice and protect consumers across the country from harm.”

T-Mobile has agreed to offer full refunds with no fee for canceling service to customers who purchased phones between March 26 and April 25. The company has also agreed to clarify its advertising so as not to deceive consumers about early termination, and to instruct its salespeople to properly inform customers. T-Mobile will also pay the state $26,046 in attorneys fees. And Ferguson makes an early mark as a pro-consumer attorney general.

All that said, there are some customers for whom T-Mobile's new plans offer significant savings: Those who routinely keep their phones for longer than two years, and those who prefer to buy unlocked phones. So while I'm with the AG that T-Mobile's claims were a bit deceptive, it's still nice to have T-Mobile's new plans as an option.