Global sales of smartphones almost tripled from 2004 to 2005, and increased by 50 per cent in the first half of 2006 over 2005, new research has reported.

According to data from In-Stat, the surge in demand for next-gen handsets is being accompanied by an escalating battle for smartphone operating system dominance. 

"There are two reasons for caution, in spite of spectacular sales," said In-Stat analyst Bill Hughes.

"Many smartphone users continue to carry the very devices that smartphones are meant to replace, and have been slow to add new applications to their devices. Most users have only downloaded a few applications."

The In-Stat report found that business users who received their smartphone through work are three times more likely to carry a second wireless phone for personal calls than other users.

In addition the study noted that many smartphones sold in 2006 serve as a combination phone and PDA device. 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.