Twitter, which offers a microblogging and social networking tool, has stopped offering part of its mobile service in the U.K., citing high prices charged by operators there. As of Thursday, Twitter said it is no longer delivering outbound text messages via its dedicated number. That feature was available to users who wanted updates straight to their mobile devices. However, Twitter's U.K. number ended up servicing all of Europe, leaving the company with a big bill. "When you send one message to Twitter and we send it to ten followers, you aren't charged ten times--that's because we've been footing the bill. When we launched our free SMS service to the world, we set the clock ticking. As the service grew in popularity, so too would the price," the startup firm said. Article