Microsoft has been showing off its next Windows Phone update, which is expected to begin rolling out this fall, and is codenamed Mango. At the same time though, the software giant is also working on the next Windows Phone updates, codenamed Tango and Apollo.

Compal Communications, which manufacturers devices for Acer and Nokia, recently signed a deal with Microsoft to build devices for Mango as well as the next-generation Tango update, according to DigiTimes. Last year, we heard of that the second major update to Windows Phone will be Apollo, due toward the end of 2012.

Of course, this can all change as we learn more about Tango and Apollo. After all, at some point Microsoft will have to release Windows Phone 8. It's very possible that one of these updates is actually Windows Phone 8, or an update to Windows Phone 8.

For now though, Windows Phone users should keep their eyes peeled for Windows Phone 7.5 (codenamed Mango). Check out our preview of the update from last week. We'll keep you posted on Tango and Apollo as we learn more.

It's generally accepted that Windows Phone is not selling well. AT&T Mobility CEO believes things will start to pick up with Mango and as the Windows Phone Marketplace gains more apps. Nokia CEO Stephen Elop meanwhile argues that Windows Phone scores better than Android and iPhone with consumers, but OEMs are doing their best work for Android. He believes that once Nokia starts doing its best work for Windows Phone, the platform will take off.