A survey released this week by research firm Ipsos Insight showed that 28 percent of mobile phone owners worldwide have browsed the Internet on a wireless handset, up from 25 percent at the end 2004.

This increase is due largely to participation by users above age 35, which analysts say suggests that the technology has gone mainstream.

Japan is leading the growth, with 92 percent of mobile phone users having browsed the Internet or downloaded e-mail at least once a month on their phone in 2005.

About four out of 10 Japanese adults went online using their mobile phones this year, up 50 percent from 2003. Next was Britain, where 29 percent used mobile phones for Internet, followed by the United States and South Korea, each with 26 percent.

However, the study reported that US and Canadian markets for online mobile phone technology are flattening out, and pointed to the popularity of notebook PCs using wireless technology as the main out-of-home Internet platforms.

The study predicts that the appeal of greater convenience and faster connection speeds could lead to changes in PC and mobile phone Internet use.

“In the long term, many of today’s PC-centric online activities could be complemented through the mobile phone or migrate to the mobile phone altoghter,” said Brian Cruikshanks of Ipsos.

The study also noted that most wireless device activities increased, including financial transactions, dowloading entertainment, and sending or receiving text messages, e-mails, and digital pictures.

“Accessing the Internet on a wireless handheld device is no longer a novelty for consumers in the major global economies. It’s becoming a common, everyday occurrence for many people,” said Cruikshanks.