Wireless subscriber growth is slowing due to market saturation, with US carriers adding only 26 mln new subscribers in the next five years to reach 266 mln in 2013. Adoption by teens and young adults will become nearly ubiquitous as the majority of the demographic already have cell phones, and 31% of parents with children ages 10 to 12 reported that their children also have cell phones, JupiterResearch says.