Months after a federal court blocked a government attempt to reduce the cost of phone calls to prison inmates, regulators have approved a less aggressive set of measures that may effectively increase what it costs for families to keep in touch with their loved ones behind bars.

Thursday's decision by the Federal Communications Commission sets new limits on what telecom companies that serve prisons and jails may charge to connect those calls. Under the new rules, inmate calls associated with state or federal prisons may not cost more than 13 cents per minute, while calls associated with jails must top out at 31 cents per minute, depending on their size.

Those rate caps are actually several cents-per-minute higher than a similar set of restrictions the FCC passed last October. Those rules would have set the rates for state and federal prisons at 11 cents per minute, for example. But it wasn't long before the caps were challenged by telecom companies who said it would cost them more to obey the rules than they could earn to cover their expenses.

After suing the FCC over the issue, inmate calling providers won a victory this spring when the U.S. Court of Appeals for the D.C. Circuit prevented some of the 2015 rules from taking effect. The ruling — and a subsequent request for review — prompted the FCC to go back to the drawing board, leading to the caps it passed in a 3-2 party-line vote Thursday.

Critics of the current system say it unjustly exploits inmates and their families, treating them as a "captive" source of revenue. In making it more difficult for inmates to communicate with their children, spouses and lawyers, the system also increases the likelihood that inmates will go back to committing crimes once they are released, they say.

"In my 18 years as a regulator, this set-up is the greatest and most distressing type of injustice I have ever seen in the communications sector," said Democratic FCC Commissioner Mignon Clyburn.

But opponents of Thursday's measure said regulators have been too eager to drive down prices in ways that undermine the ability of jails and prisons, which charge telecom operators their own fees, to operate.

"Some [facilities] enroll inmates into a biometric voice system while others employ real-time call monitoring," said Republican FCC Commissioner Ajit Pai. "The evidence submitted by sheriffs, inmate calling service providers, economists, and state commissions all demonstrated that the costs to facilities … are real and substantial."

Securus Technologies, one of the inmate calling services that had sued the FCC, declined to comment Thursday. Another, Global Tel*Link, did not immediately respond to a request for comment.

"This is an issue that has gone on for far too long and abused far too many people and families," said Tom Wheeler, the FCC's chairman.