Verizon and Sprint customers have until Dec. 31 to seek a share of the $120 million allocated for consumers under national "mobile cramming" settlements announced earlier this year.

Under the settlements Verizon or Sprint customers who experienced unauthorized third-party charges on their cell phone bills dating back to July 2010 may be eligible for refunds.

Verizon customers can submit their claims at www.CFPBSettlementVerizon.com.

Sprint customers can submit their claims at www.SprintRefundPSMS.com.

The Verizon and Sprint settlements, announced in May, were the latest in a nationwide effort by the attorneys general of all 50 states and the District of Columbia, the Consumer Financial Protection Bureau, the Federal Communications Commission, and the Federal Trade Commission to curb the practice of mobile cramming. Similar settlements were reached with AT&T in October 2014 and T-Mobile in December 2014.

All four carriers announced that they would stop billing customers for commercial premium text message subscription services (the largest source of mobile cramming) in the fall of 2013 after the states began investigating.

Consumers who experienced “cramming” usually were charged small one-time fees or monthly subscription fees of $9.99 per month for premium text message subscription services involving ringtones, horoscopes, trivia, or sports scores that they did not request. Frequently, the charges occurred after consumers entered their mobile phone numbers online.

Consumers who have questions about Verizon claims should visit www.CFPBSettlementVerizon.com or call the claims administrator at 888-726-7063. Consumers who have questions about Sprint claims should visit www.SprintRefundPSMS.com or call the claims administrator at 877-389-8787.