The typical U.S. mobile subscriber sends and receives more SMS text messages than telephone calls, according to research released Monday by Nielsen Mobile. 
During the second quarter of 2008, a typical U.S. mobile subscriber placed or received 204 phone calls each month.  In comparison, the average mobile customer sent or received 357 text messages per month — a 450% increase over the number of text messages circulated monthly during the same period in 2006.