A recent Gartner study estimates that 189 billion mobile messages have been sent by U.S. mobile-phone subscribers in 2007. It forecasts 301 billion mobile messages sent in 2008. C/net reports.

"Iff correct, those figures would still account for only a small fraction of the 2.3 trillion messages to be sent across major markets worldwide in 2008 (a 19.6 percent increase from the 2007 total of 1.9 trillion messages). Asia is the biggest mobile-messaging market worldwide. China is in the lead, with approximately 560 billion SMS messages sent in 2007, followed by the Philippines' 430 billion and Japan's 190 billion.

The vast majority of the 189 billion mobile messages to be sent in the United States are expected to be SMS text messages, with an average use of about two SMS messages per U.S. subscriber per day.

... Despite the continued growth of SMS usage, however, Gartner expects growth rates to slow as direct mobile connections are becoming increasingly cannibalized by mobile-IM communities and social-network portals."

Source: http://www.textually.org/