Microsoft has announced that the next version of its mobile phone OS, Windows Phone 8, will share core technology with its forthcoming desktop and tablet operating system, Windows 8.

However, although this means the operating systems should integrate more seamlessly, the downside is that owners of devices running Windows Phone 7.5 won't be able to upgrade.

Instead, Microsoft is offering these users a bridging OS, Windows Phone 7.8, allowing them to still experience the features that are within the reach of their devices' hardware, such as the new Start screen.

"Windows Phone 8 is a generation shift in technology, which means that it will not run on existing hardware,” Microsoft corporate vice president Joe Belfiore says in a blog post.

"BUT we care deeply about our existing customers and want to keep their phones fresh, so we're providing the new Start screen in this new update.

This new Start screen offers a new palette of theme colours, as well as three sizes of Live Tiles.

Besides the Start screen, Windows Phone 8 will offer support for new handset technologies like higher screen resolutions, removable MicroSD cards and NFC wireless sharing.

The new OS will also come with Internet Explorer 10, the same browser that's going to be on offer in Windows 8.

"We've based the next release of Windows Phone on the rock-solid technology core of Windows 8,” Belfiore says.

"It means Windows Phone and its bigger sibling will share common networking, security, media and web browser technology, and a common file system.

Belfiore also takes the opportunity to acknowledge that the Windows Phone Marketplace has officially reached 100,000 apps and games, and notes that the new OS will also support changes targeted at developers, such as in-app payments.

Nokia, HTC, Samsung and Huawei are all confirmed as manufacturers working on devices running the new OS.

Handsets should start arriving before the end of the year; with Windows 8 and the newly announced Windows Surface tablet all due out before then as well, it's going to be a busy six months for the technology giant.