Calls to 411, formerly a free service, have made money for phone companies. Carriers collect about $6 billion a year on directory assistance for traditional phones, Pierz said. She said adding cell phones could generate another $1.9 billion year, which would be shared by phone companies and the companies that administer the service for them.
Pierz said the idea is gradually gaining acceptance. About 10.5 percent of the cell phone users surveyed in her company's ongoing study said they would list their numbers -- up from 2 percent a year ago, she said. Consumers are still learning how the system works, and that education process will be a slow one, she said.
The survey found that more consumers might sign up if carriers took additional steps to protect privacy. Technologies could add layers of privacy -- allowing only those with passwords to get a phone number, or connecting calls without giving the number -- although the carriers aren't currently considering those measures, she said.
Cell phone user Russell Raub says he'll never give in.
"I guarantee you I will go to my grave never having opted in," said Raub, who lives outside of Gettysburg, Pa.
He's written three letters to AT&T Wireless Services Inc. expressing concern that the wording of his contract would allow the company to include him in a directory without notice. He's also written to his representatives in Congress asking for a law to protect his rights to keep his number private.
"What worries me is that someone that I may have no business or personal relationship [with] could start harvesting my number and start using it" at his expense in incoming minutes, Raub said. He pays about 70 cents a month to keep his home number unlisted and has both his cellular and home numbers in the do-not-call registry. AT&T Wireless assured him in an e-mail that he would be listed only if he wants to be, but he's worried that will change eventually.
Consumer groups share Raub's concern that the industry won't protect consumers' privacy and will eventually include customers' numbers automatically or charge them to keep their numbers unlisted.
"There's no guarantee -- that's why we want regulation," said Adam Goldberg, a spokesman for Consumers Union.
"As long as you're paying for that call, you should be able to control who's calling you," said Carl Hilliard, president of the Wireless Consumers Alliance, a consumer advocacy group near San Diego. "I don't know anyone who wants to get more calls."
