<p>LOS ANGELES TIMES Monday May 20, 2013 1:43 AM Francine Orr | Los Angeles Times</p><p>Mobile messaging apps such as WhatsApp have caught on with such force that users are sending trillions of messages a year through them, avoiding traditional texting fees.</p><p>SAN FRANCISCO WhatsApp is one of Silicon Valley's most buzzed-about companies, yet it activelyavoids the spotlight, operating out of a small office in Mountain View, Calif., with no sign on thebuilding entrance or on the office door.</p><p>Unlike most startups eager for media attention, WhatsApp says it doesn't want or need it. Itspopular mobile messaging application has spread so quickly by word of mouth that in just four yearsit has amassed hundreds of millions of users who collectively send as many as 18 billion messages aday.</p><p><a href="http://www.dispatch.com/content/stories/business/2013/05/20/messaging-apps-skirt-carriers-fees.html">Keep reading...</a></p>