Sprint and Verizon Wireless, two of the nation’s three largest wireless carriers, will offer refunds to affected customers through a combined $158 million joint state-federal settlement over allegations the companies engaged in “mobile cramming,” or placing unauthorized charges on consumers’ mobile phone bills.

Sprint and Verizon will make combined payments of $360,000 to Iowa Attorney General Tom Miller’s consumer education and litigation fund.

Consumers who have been “crammed” often have charges, typically $9.99 per month, for “premium” text message subscription services such as horoscopes, trivia and sports scores that consumers have never heard of or requested.

Sprint and Verizon are the third and fourth mobile telephone providers to enter into a nationwide settlement to resolve allegations regarding cramming. Miller and state attorneys general reached similar settlements with AT&T in October 2014, and T-Mobile in December 2014.

Under the terms of the settlements, Sprint will pay $68 million and Verizon will pay $90 million. Of these amounts:

• Sprint and Verizon will provide $50 million and $70 million, respectively, to consumers who were victims of cramming. Sprint and Verizon will each distribute refunds to eligible consumers through redress programs that will be under the supervision of the Consumer Financial Protection Bureau.

• Sprint will pay $12 million to the state attorneys general, including more than $206,000 to Iowa, and $6 million to the Federal Communications Commission.

• Verizon will pay $16 million to the attorneys general, including more than $154,000 to Iowa, and $4 million to the FCC.

The four carriers must also take steps designed to ensure they only bill consumers for third-party charges the customers authorized.

Consumers can submit claims under the redress programs by visitingwww.SprintRefundPSMS.com and/or www.CFPBSettlementVerizon.com. On those websites, consumers can submit claims, find information about refund eligibility and how to obtain a refund, and request a free account summary that details Premium Short Message Service purchases on their accounts.

The claim deadline for the Sprint and Verizon settlements is Dec. 31.