SAN FRANCISCO — A federal judge has rejected class action treatment for a suit against three text messaging firms on behalf of consumers who claim they were charged for subscriptions they never requested.

U.S. District Judge William Alsup on Monday denied a motion to certify two proposed classes to pursue litigation against Mobile Messengers America Inc., mBlox Inc. and Motricity Inc. for alleged violations of the Telephone Consumer Protection Act. The law prohibits calls or text messages to mobile phones using automatic dialing systems without consent.

Plaintiffs lawyers at Konenberger Rosenfeld accused the texting firms of charging cell phone users for unauthorized messages, ranging from horoscope advice to trivia questions, a practice known as “cramming.” Defense lawyers claimed consumers had enrolled in the subscription plans through various web sites.

Alsup held that plaintiffs had not shown common issues trumped the need for an individualized examination of consent. That failure “is a showstopper,” Alsup wrote, citing defense evidence that more than 1.5 million subscribers had consented to the messages.

Lawyers at Cooley and Venable represented Mobile Messenger. Motricity was represented by Crowell & Moring. And mBlox was represented by Chicago firm McGarry & McGarry.

Contact the reporter at mtaves@alm.com.