Microsoft has released a list of five mobile phones which are eligible for a Windows 10 operating system download. 

The list includes the AT&T's Lumia 640 and 640XL, Verizon's Lumia 735, Sprint's 635 and the unlocked version of the Lumia 635. The first three are available for $249.99, $79.00 and $49.00 respectively while Sprint's version is free with a new contract and the unlocked device costs $129.00. 

The Redmond, Washington-based technology company is set to host a hardware-focused event on Oct. 6, where developers are expected to reveal more information about mobile phones eligible for a Windows 10 download. This comes weeks after it was announced that Microsoft will release its first non-patch update for Windows 10 later this year. 

The update, dubbed "Threshold 2," is set for an early November release date, WinBeta reports. The download is said to include a desktop messaging application as well as bug fixes for current versions of the operating system. 

Threshold 2 has also been slated to include better gaming capabilities. 

Windows 10 has been available for over two months now and has generated mixed reviews from users around the world. 

Some have touted its newest applications, such as Task View (a virtual desktop system) and its support for human recognition (via face images and fingerprints). Others, however, have been heavily critical of the new operating system's privacy policies. Among these professional pirates who remain weary about using the update.

Notable torrent groups like iTS and FSC have banned users from using Windows 10, citing concerns of privacy and security. 

"Amongst other things windows 10 sends the contents of your local disks directly to one of their servers," iTS wrote in a statement. 

"Obviously this goes way too far and is a serious threat to sites like ours which is why we had to take measures."