Smartphone unit sales almost tripled from 2004 to 2005, and increased by 50% in the first half of 2006 over 2005, reports In-Stat. Many smartphones sold in 2006 serve as a combination phone and PDA. Others have power and performance comparable in capability to many laptops. Most of the smartphones sold globally, however, only enable the user to access the capabilities of basic wireless phones. US smartphone customers are about evenly split between Windows Mobile, BlackBerry OS, and Palm OS.