Nokia remains the world's leading builder of cell phones but most of these are so-called feature phones, lacking the sophistication, software and prices of smartphones like 's or RIM's more recent BlackBerry products. The analyst suggested that Nokia's Symbian OS be relegated quickly to the low- and mid-range product lines, to defend against encroachment by devices running Google's fast-growing OS. Eventually, Ahmad said, economies of scale will let Nokia shift Windows Phone into this market also.

Ahmad's recommendation was in that appeared Monday in The Financial Times.

Nokia's share of the global smartphone market fell to 31% in Q4, down from 40% a year earlier; the company's profit plunged even more, by 21%, according to The New York Times.

Ahmad argued that Microsoft needs a high-volume smartphone maker like Nokia, which would be focused entirely on Windows Phone. Currently, handset makers such as HTC, Samsung and LG also are heavily invested in Android phones. In January, Microsoft revealed that in eight weeks, it had of Windows Phone 7 to its handset customers. There are still no retail figures on the number of Windows Phone handsets which have been activated on mobile operator networks.

John Cox covers networking and mobile computing for Network World.