Despite Nokia's Lumia 710, 800 and 900 devices launching to warm receptions in Europe and the U.S., telecom operators in Europe remain unconvinced about the success of the devices. Speaking to Reuters, the operators see no reason why the Lumia should do better than the iPhone or Android smartphones.

The telecom operators said the Lumia devices "were not good enough" when compared to the iPhone and Samsung Galaxy devices.

The Lumia 900 launched in the U.S. on AT&T this month, in a bid to increase Nokia's marketshare from its current one percent. The device has been available for two weeks, and AT&T said demand is strong. The carrier had earlier said the 900 launch would be the biggest ever.

Lumia critics, however, say that sleek form factors are overpriced as the products aren't innovative. Other criticisms are a lack of "marketing dollars" behind the phones, and image problems caused by early glitches in the battery and software.

The operators also said Nokia's focus on Windows Phone isn't paying off. The company shifted focus away from its Meego and Symbian operating systems as Stephen Elop, the company's chief executive, took over.

"No one comes into the store and asks for a Windows Phone," an executive in charge of mobile devices at a European operator - which has sold the Lumia 710 and 800 since December - said.

"Nokia have given themselves a double challenge: to restore their credibility in terms of making hardware smartphones and succeed with the Microsoft Windows operating system, which lags in the market.

"If the Lumia with the same hardware came with Android in it and not Windows, it would be much easier to sell," he added.

However, carriers do want competition to iPhone and Android devices to offer consumers more choice and to give carriers a stronger bargaining position with phone manufacturers. Carriers heavily subsidize devices before they hit shelves.

U.S. operators buy approximately 90 percent of mobiles, with European carriers buying 50-70 percent, market researcher Gartner and Bernstein Research said. Operators make a return on investments through one or two year contracts.

(reported by Jonathan Charles, edited by Surojit Chatterjee)