Summary Box: O2 accidentally exposes phone numbers

WHOOPS: An untold number of U.K. residents may have unwittingly broadcast their numbers to sites across the Web while browsing the Internet with their cellphones during the past two weeks.

WHAT HAPPENED: Mobile service provider O2 says a glitch had exposed the numbers of smartphone-toting customers who connected to the Internet over the company’s network.

REACTION: O2 says it has fixed the problem and apologized for any concern caused. The Information Commissioner’s Office, Britain’s data protection watchdog, says it’s looking into the potential breach.