Microsoft's new Windows Phone operating system update codenamed 'Apollo' won't be available for old Windows Phone users. The Redmond-based company confirmed this news at its Windows Phone Summit. But the company has also ensured the users that there will be an update for these devices named Windows Phone 7.8.

The update will be packed with some new features from Windows Phone 8 operating system including new colorful themes and the new start screen. But this update may not be enough for heartbroken Windows 7.5 users as most of the killing Windows Phone 8 features won't be available there. All these updates will be delivered to users directly and can be downloaded via Wi-Fi.

People who just started to use this operating system won't be happy about it, especially Nokia Lumia 900 users as these phones won't be able to run any app specially designed for Windows Phone 8. There were rumors roaming around about why Microsoft is not releasing Windows Phone 8 update for 7.5 users that it requires improvements in hardware. Windows Phone 8 requires multi-core support and high resolution which is not available in old devices. Most of the old Windows operating system based phones are rocking WVGA screen with single-core.

ZDNet has also confirmed on Wednesday that apps designed for Windows Phone 8 won't support Windows Phone 7.x operating system. "New applications compiled specifically for Windows Phone 8 will not be made available for Windows Phone 7.x devices."