clipped from: www.marketingcharts.com 
Mobile subscribers in the US initiate and receive significantly more SMS text messages than mobile telephone calls, with teens sending more text messages than any other age group, according to research from Nielsen Mobile.
As of the second quarter, a typical cell-phone user in the US sent or received 357 text messages per month, compared with placing or receiving 204 phone calls. Though the number of calls has remained relatively steady, the number of text messages is up 450% from two years ago.