Dr. Dan Stambor keeps a cell phone for emergencies, but he doesn’t use it much and rarely turns it on. He wouldn’t know how to send a text message even if he wanted to, he said.

So the Seattle doctor was surprised when he opened a recent phone bill and found a $9.95 charge for premium text messaging.

“I don’t know how to do text messaging,” Stambor said. “I don’t know where (the charge) came from.”

After explaining to Verizon Wireless, his carrier, that he didn’t authorize the charge, he said a customer service representative reversed the charge and told him it was from a third-party service. She also offered to disable his text messaging so it wouldn’t happen again.

What is premium text messaging? How can one be billed without signing up?

Premium text messaging refers to special marketing programs that charge a fee to subscribe. It allows you to sign up for sports score alerts, weather updates and daily horoscopes, download ringtones or vote in TV contests like American Idol. Charges range widely, and the fees are usually on top of standard text messaging fees. Most programs require you to opt in, but some consumers, like Stambor, say they were charged without agreeing to such services.

“Some customers may have signed up by mistake, but others are the victims of a mobile scam,” said Jay Edelson, a Chicago attorney representing consumers in several lawsuits related to premium text messaging. “We’ve had cases where people have mobile devices that can’t get text messages and they’re being billed.”

It’s often not clear on the cell phone bill what the charges are for and why, he said. If you look into it further, you may realize the carrier and the content provider don’t know either, he said.

Some content providers or their affiliates sign up people for services without consent. It’s easy to do because some services only require entering a cell phone number to subscribe, leaving it open for anyone to enroll you, Edelson said.

Other times, you fill out a form or enter a contest that asks you for a cell phone number, and “you may find that the tiny print at the bottom also subscribes you to a linked text messaging service.”

Or you may have a “recycled number” and get billed for services to which the previous owner of the number had subscribed.

Georgia Taylor, a spokeswoman for Verizon Wireless, said it’s also possible consumers inadvertently opted in when they didn’t mean to or that someone opted in for them.

“If people have tried to opt out and they’re still having problems, they should call Verizon,” Taylor said. “If you’re getting unwanted (text messages), we want to hear from you and we’ll credit you.”

Taylor said Verizon follows the best practices guidelines of the Mobile Marketing Association and takes action against those who violate the program.