Before launching their Lumia line of smartphones in the U.S. this year, Nokia and Microsoft introduced the Lumia 710 and Lumia 800 in the UK and other European countries last fall. But according to a report Tuesday from Reuters, the Windows Phone-based Lumia devices aren’t being well-received by European telco companies, which could mean the loss of a critical market for both Nokia and Microsoft.

Four telcom operators based in Europe reportedly told Reuters that the Lumia line-up lacks a sufficient marketing campaign, is overpriced, and suffers from "image problems" caused by an unreliable battery. They also said that demand for the series’ software, Microsoft’s Windows Phone OS, is simply not enough to compete seriously against Apple’s iOS and Google’s Android platform.

"No one comes into the store and asks for a Windows phone," an executive at a European operator, which has sold the Lumia 800 and 710 since December, told Reuters.

[Related: Nokia, Microsoft Launch Lower-End Lumia Smartphone]

Nokia declined to comment, and Microsoft did not immediately respond to a request for comment.

The executive, who was quoted anonymously in the article, stressed the success of the Windows platform on traditional notebooks and desktop PCs, telling Reuters that it allows you “to do tons of cool things.” But in the mobile world, customers seem to gravitate more toward Android.

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

Android’s worldwide market share grew to more than 50 percent last November, according to a report from industry analyst Gartner. While Nokia’s original homegrown OS, Symbian, was second behind Android with 16.9 percent, its share dropped significantly from the 36.3 percent it held in 2010.

Apple’s iOS accounted for 15 percent and Windows Phone accounted for a meager 1.5 percent.

Nokia and Microsoft launched the Lumia smartphone series as part of a larger agreement the two made last February. Under the alliance, the companies agreed to jointly develop a new mobile device ecosystem based on Microsoft’s Windows Phone 7 platform rather than Nokia’s struggling Symbian OS. The partnership was intended to yield new devices that could rival those of Apple and Google, but also to re-position Nokia and establish Microsoft as industry leaders in the smartphone space.

Despite the tough competition in Europe, the Lumia line-up has met with some success in the U.S. AT&T, the exclusive U.S. carrier of the higher-end Lumia 900 that launched last Sunday, told Reuters that the new device has already sold out in many of its store. T-Mobile, the exclusive carrier of the lower-end Lumia 710, also said that the device is among its most popular phones.