Windows 10 for phones which was showcased by Microsoft at an event held on 21 January at its Redmond headquarters, is being eagerly awaited by Lumia smartphones owners.

However, not it seems like Microsoft's most expected mobile OS, along with certain important features, will not reach all of the currently existing Lumia smartphones.

According to the official Lumia Conversations blog, Microsoft states that all of the current Lumia smartphones will not feature each and every Windows 10 functionality, as these are dependent on the hardware configuration of devices.

"Like any upgrade to a new platform, not every phone will upgrade or support all possible Windows 10 features, and certain features and experiences will require more advanced future hardware," the blog quoted a company official as saying.

"Our goal is for the majority of the Lumia phones running Windows Phone 8 and 8.1 to join the Windows ecosystem," said corporate vice president of sales for Microsoft Mobile Devices group Chris Weber, in the Q&A published on the site.

However, at this point, Microsoft has not mention the exact Lumia models that are confirmed for the Windows 10 upgrade, but according to a GSMArena report only certain Lumia handsets will receive Windows 10.

The models mentioned in the report include, the Lumia 435, Lumia 735 and 930, all of which have also figured in the official Lumia Conversations blog.

"For example, you can get the budget-friendly Lumia 435, the selfie-happy Lumia 735, or the gorgeous gold-edition Lumia 930–and you will be able to upgrade to Windows 10 as it becomes available," Weber said.