Microsoft may be heading for a disappointment where its Windows Phone 7 OS is concerned, as Phone maker HTC and wireless carrier T-Mobile remained evasive on the issue of using the OS in the HD2 smartphone soon to be launched by them.

On Tuesday, when HTC and T-Mobile declared the launch of the eagerly awaited HD2 smartphone in the U. S., the companies maintained that as for now, they had no plans of using the Microsoft's Windows Phone 7 OS in the phone.

When the HD2 phone was released in Europe in October of last year, it employed the Windows 6.5 Phone OS. However, soon Microsoft declared that the Windows 6.5 phone OS could not be upgraded and a new Windows 7 phone OS would be made available later this year.

However, HTC and Tmobile have decided to release the HD2 smartphone in US without waiting for Microsoft to release of the new OS.

T-Mobile spokesperson Jon Eliav said, "We don't know when the first [Windows 7 Phone OS] device is coming out". He also maintained that HTC has not made it official yet whether or not it will be using the operating system in its upcoming HD2 Smartphone.