This report, by Amanda Lenhart, from the Pew Research Center’s Internet and American Life Project surveyed 799 teens ages 12 to 17 years old about their mobile phone ownership and usage.
"Teens are fervent communicators. Straddling childhood and adulthood, they communicate frequently with a variety of important people in their lives: friends and peers, parents, teachers, coaches, bosses, and a myriad of other adults and institutions. This report examines the tools teens use to communicate, with a particular focus on mobile devices, and then places the use of those tools in the broader context of how teens choose to communicate with people in their lives.
The volume of texting among teens has risen from 50 texts a day in 2009 to 60 texts for the median teen text user. In addition, smartphones are gaining teenage users. Some 23% of all those ages 12-17 say they have a smartphone and ownership is highest among older teens: 31% of those ages 14-17 have a smartphone, compared with just 8% of youth ages 12-13."