Most of the time I update using Nokia Care Suite. Did some work on it before, fixing some cab injected phones that aren't getting the firmware updates.

Just finished on another one that had problems with updates, because it came with the firmware previous from 12070.

Updating the Lumia sometimes is strange. I have a lumia 800 with the firmware previous to 12070. Every time I connect to Zune, it keeps telling me I have the latest firmware, which is impossible since I am missing 12070.

So I used Nokia Care Suite and lo and behold, the 12070 update is the latest update that is available, so I updated it. After 12070 is installed, Nokia Care Suite now tells me that 12070 is the latest firmware they have.

Fired up Zune, and the rest of the updates to 12070 are found and installed. So there are two actual update repositiory, one is with Microsoft and the other one is with Nokia.