Microsoft has kept its promise to move Skype for Windows Phone out of beta by April, first announced at Mobile World Congress this year. New features, such as the ability to search for contacts and add them on Skype, come with v1.0.

Microsoft had introduced the beta of Skype for Windows Phone back in February this year, and said the app would run on devices running Windows Phone 7.5 or above.

Other features include the ability to call landline phone numbers, a faster boot-up time and bug fixes. The app supports making calls over Wi-Fi, 3G and 4G along with the ability to enable group messaging.

However, the app has to be running to receive Skype calls. Microsoft said this is because of limitations in its own OS and Skype, though there's every chance this could change with the release of Windows Phone 8.

Microsoft hasn't rolled out Skype across all of its services but, the launch of Windows Phone 8, along with Windows 8, could bring greater integration across platforms. Apple offers Facetime between mobile and desktop devices.

Rumours suggested the app would remain a standalone service during the Windows Phone 8 launch, though there's a chance it could launch before Microsoft's upcoming desktop operating system.

200 million people use Skype every month. The company was founded in 2003, based in Luxembourg. Microsoft acquired the service in October last year in a deal worth $8.5 billion

Skype for Windows Phone can be downloaded now from the Windows Phone marketplace. Skype said it may take up to 48 hours for the app to be available in all Windows Phone marketplaces.

The app has been "tested and certified" on seven models, including the Nokia Lumia 800 and 900 and the Samsung Focus S.

(reported by Jonathan Charles, edited by Dave Clark)