The market leader is still Symbian, according to ABI Research. But other smartphone with Windows Mobile or Linux would take Symbian's market share because the Symbian is rely heavily on Nokia mobile phone and also largely in GSM network only.

Microsoft hopes to overtake Symbian with its Windows CE operating system and Windows Mobile middleware. Its "pro" is its enterprise focus. It interfaces well with Microsoft Exchange Server, so prevalent in business operations. However - the con - Microsoft likes to control as much as possible of its end-users' experience, and so do operators, who want to fully customize the user interface.

Then there's what some call the "wild card": Linux. In its favor, it's highly customizable, and inexpensive. But while it has been embraced by market leaders in Asia, it's still an unknown quantity elsewhere.

Last year ABI Research suggested that the Symbian OS would lose market share, and today, Solis confirms that forecast. "Symbian is still by far the market leader," he says "but more Windows Mobile phones are reaching the market. And we are bullish about the prospects for a rebranded Palm user interface running over Linux (alongside many other Linux OS solutions) taking some of Symbian's market share."