A new study claims that mobile Web browsers, including the open-Internet variety, will grow exponentially to 1.5 billion units by 2013.

The findings, from ABI Research, also show that the number of open-Internet browsers will grow from 76 million units in 2007 to an estimated 700 million by 2013. Smartphones incorporating browsers that support AJAX and RSS technology as well as mobile-optimized Web sites will drive mobile Web browser adoption.

"You're always going to get optimized experiences for the mobile phone -- you have a smaller screen and no mouse," said ABI research director Michael Wolf. "But as things like the iPhone influence, you're going to have more of a PC-like experience."

The focus currently for mobile browser developers is to take advantage of the latest Web standards while also developing offerings tailored towards the experience of using a browser on a mobile phone.

New products from Opera, Openwave and Access along with open source offerings such as Webkit are designed to let consumers access the Internet without the typical mobile restrictions.

However, ABI cautioned that Web usage has a long way to go before it closes the gap with PC-based browsers despite the efforts of browser vendors and handset manufacturers.

A key obstacle, as mentioned in ABI's Mobile Browser Market report, is the lack of key plug-ins such as Flash on many handsets.

Also, the constraints of many mobile phones compared with the PC mean that the open-Internet browser segment browser developers including Skyfire still need to rely on server-assisted architecture for transcoding and Web acceleration.

"There's always going to be limitations with phones," Mr. Wolf said. "Even as phones get more powerful, Internet sites are going to get richer. So I think to say that phones are going to catch up with today's Internet -- they're going to close the gap, but maybe not ever entirely."

But there is a lot of momentum for Web content on mobile phones, according to ABI.

The move towards Web-based applications means that browser and Web services engines will become increasingly important for mobile, whether these are in a commercial browser implementation or a customized widget.

"We definitely see a move towards Web applications and a move away from native applications," Mr. Wolf said. "I think the browser, or the underlying engine of the browser, will be an important part of this transition."