As smartphones like the iPhone and Android take over the mobile Web, the amount of data traffic going over cellular networks is expected to grow 40-fold over the next five years. UK firm Coda Research Consultancy forecasts that in the U.S. alone mobile handset data traffic will grow from 8 terabytes/month this year to 327 terabytes/month in 2015. That amounts to a 117 percent compound annual growth rate.

A lot of that data will come in the form of mobile Web browsing, with the biggest contributor expected to be mobile video. By 2015, mobile video will account for 68.5 percent of all mobile data usage in the U.S. (or 224 terabytes/month). Coda estimates that 95 million mobile handset subscribers in the U.S. will be watching video on their phones in five years out of a total of 158 million mobile internet users.