According to a new report from ZDNet, which cites trusted sources, the oft rumored Tango update to the Windows Phone platform is real, is not Windows Phone 8, and will come after Mango.

Even more, it should be a less beefy update (when compared to Mango), and is often mentioned in conjunction with Nokia. It could be, ZDNet says, and TNWmicrosoft finds this reasonable, that Tango is the low-cost version of Windows Phone that Nokia and Microsoft want to make available in a number of markets.

The timing on all of this makes sense. Microsoft plans to release a single major update a year to Windows Phone. Mango is this year’s upgrade, and is technically Windows Phone 7.1, even though handsets running the updated build will be labeled Windows Phone 7.5 phones. Apollo, Windows Phone 8, is not expected until late 2012 (in time for the holiday season).

So, if Tango was to come after Mango and before Apollo, to keep with the ‘one big update per year’ plan, Tango would have to be smaller, and more specialized, exactly what we are hearing.

And Nokia has always said that it had a deal with Microsoft to make changes to the Windows Phone operating system that went above and beyond what other OEMs had, so Tango could be what the two companies are cooking up together. Nokia will, of course, release full-featured Windows Phone handsets.

Mango itself has just been released to manufacturing, so it is unlikely that we will hear much on Tango or Apollo from Microsoft itself for some time. But it appears that the leaks are beginning to spring, so we should have more to chew over, especially once Mango sorts itself out.

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