As a result, Symbian will develop an Exchange Server ActiveSync protocol – plug-in – for the Symbian OS messaging architecture to enable licensees to include direct over-the-air (OTA) synchronization capabilities for Exchange Server 2003 e-mail, calendar, contacts, and data to their handsets.

Terms of the deal were not disclosed.

The agreement raises eyebrows because Microsoft and Symbian have fiercely competed against one another through the years. In fact, several cell phone manufacturers formed Symbian to help counter the software giant's expected assault on their turf.

With over 14 million handsets shipped last year and about 25 million in circulation, Symbian—by far the number one smartphone vendor—has done remarkably well so far. Number two Microsoft, on the other hand, has struggled to get handset manufacturers and carriers, in particular, to support its intelligent handset platform.

Of course, smartphones account for a very tiny percentage of the world's 1.2 billion mobile phones. JupiterResearch recently predicted, however, smartphone shipments would grow at a compound annual growth rate of 28 percent through 2009, rising to 9.3 percent of the total market by the end of the decade; a significant chunk of a market expected to top 600 million units by that time

Symbian said the deal makes yet another messaging and data access solution available to its customers. For example, Symbian also supports Research In Motion's synchronization services through that company's BlackBerry Connect program, in addition to the Open Mobile Alliance (OMA) Data Synchronization protocol as implemented through a number of different vendors.

The company's Executive VP of marketing Marit Doving asserted, "Developing Microsoft's Exchange Server ActiveSync protocol plug-in for Symbian OS continues Symbian's drive to offer the broadest possible choice of e-mail and PIM solutions. This will help all Symbian OS licensees meet the needs of the enterprise market."

The leading smartphone platform developer isn't the first to partner with Microsoft on Exchange Server compatibility. palmOne licensed the ActiveSync protocol for its Treo smartphones, and even top-selling cell phone and smartphone manufacturer (not to mention Symbian co-owner) Nokia recently did the same for its future handsets.

Nokia can now build a direct OTA synchronization link between handsets running its Series 60 and Series 80 software platforms and Microsoft Exchange Server 2003.