Microsoft said that it has identified the source of the 'phantom data' problem with Windows Phone 7 which caused some users to suffer megabytes of data consumption despite being connected to Wi-Fi.
The company had earlier said that it was investigating the claims following a number of reports appearing on Paul Thurrott's Wndows super site.
When pressed by local blog site seattlepi.com, Microsoft released a statement in which the software giant blamed the data usage on an unnamed "third-party solution" which it said was commonly accessed from Windows Phones.
"We are in contact with the third party to assist them in making the necessary fixes, and are also pursuing potential workarounds to address the configuration issue in case those are needed," the company said.
It's not clear if the data consumption is the result of applications which users have installed on their phone. However, the fact that the data usage continues over a 3G connection despite being connected to Wi-Fi would suggest a software flaw in the operating system.
"We are continuing to investigate this issue and will update with additional information and guidance as it becomes available," they said.