Microsoft, which has been carving a larger slice of the mobile device OS market, is developing a product codenamed 'Crossbow', which will incorporate features such as instant messaging, a Microsoft executive confirmed today.

Crossbow will have strong links with Office 2007 and Exchange 12.0, Microsoft's pending office application suite and email server, said Pieter Knook, senior vice president for the mobile devices and telecoms sector. Crossbow would be the successor to Windows Mobile 5.0, released in May 2005.

Crossbow will take aim at the Symbian and BlackBerry operating systems. The OS will contain a new mobile version of Office Communicator, an Office 2007 enterprise communications application, that includes instant messaging on public and private networks, Knook said.

"As the Office [2007] PC versions of those applications improve, we're tracking that on the Windows Mobile side," Knook said.

Knook said it's premature to say when Crossbow would be released, but that the company plans for an annual mobile OS release. Mobile operating systems are also complex because operators must be tested often to ensure their systems can work with a new OS, aprocess that can cause a six- to 12-month delay after a release, Knook said.

That process is nearly complete for the push email capability of Windows Mobile 5.0, Microsoft's slow assault against BlackBerry email that may now start to bear fruit. The company's push email capability depended on software upgrades on the telecom-operators' side, as well as new versions of Exchange Server 2003 and Windows Mobile 5.0.

Those upgrades are nearly complete, Knook said. "You're getting to the point right now where this quarter is really where the whole offer comes together," he said.

Microsoft is hoping to nudge BlackBerry aside on costs and convenience for administrators. Knook estimates an enterprise deploying mobile email with 20,000 users could save $1.5m (about £840,000) in software purchases alone, plus additional costs on licensing over BlackBerry, he said.

Microsoft is counting on strong connections with device manufacturers to strengthen its position with those enterprises already using Exchange but with a BlackBerry server. The push email feature would enable those companies to eliminate the BlackBerry middleware, which also consolidates their support structure, Knook said.

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