The information comes via Navifirm+ which shows uploaded files to Nokia servers. There we can clearly see the 8779 update (slightly higher than the 8773 OS on some Windows Phones) with the AT&T naming in the files.

We’re in the finally stages of waiting for AT&T and Nokia to push out the much anticipated ‘Tango’ update for the Lumia 900 Windows Phone. Windows Phone ‘Tango’ will feature improvements to MMS including multiple messages and audio file support in addition to other minor changes. In addition, the inclusion of new firmware from Nokia should allow some of Nokia’s exclusive apps like Counters and Contact Share to finally work as well as flip-to-silence and other bug fixes and enhancements .

The Tango OS + firmware update on Nokia's servers

We’re currently downloading the files ourselves and will look to have a walk through shortly if we are able to flash our phone. Stay tuned.

While the files are now on Nokia’s servers, it doesn’t the mean the update will be rolling out through Zune immediately—in fact it could still be anywhere from hours to days to even a few more weeks. Still, the fact that Nokia has seemingly locked-down the OS and firmware update is big step to final release.

********************

Update: You can read our initial thoughts and see our hands-on video of the Tango update here.

Note: if you want to flash this ROM, it will wipe the device as this is not a straight forward update but rather the whole ROM image. You will also need to use the third-part Nokia Care Suite program to do the flash which could damage the phone.

Thanks, Travis, for the tip!