Berg acknowledged that the sales of 1.5 million devices notwithstanding, WP7 has a long way to go.

"We know we have tough competition," Berg said. "We're in the race ... and we're in it for the long run."

Gold was dubious.

"I don't know what Microsoft's magic number it is, but at some point in the next eight to 12 months, if sales don't increase, they'll have to look and ask themselves if this is too expensive for them," Gold said.

"They're not setting the world on fire, and if they can't accelerate sales, Ballmer will have to say, 'We're getting our clock cleaned, why are we in this business?'" Gold added.