Nokia is preparing to push out the Windows Phone 7.5 Refresh, aka Tango, update to the Lumia 710. OS version 8773 can already be found over at Navifirm with a large selection of builds for different operators and countries. There are two builds found on Navifirm: 1600.3030.8773.12120 / 1600.3031.8773.12121. 8773 indicates the OS version, ie WP 7.5 Refresh, and 12120/12121 indicates the firmware build. This many different builds on Navifirm could only mean that a worldwide rollout can be expected soon.