Ok so I was previously running wp 8.1 preview for developers with Lumia Cyan and when i started having issues with audio cutting off for no apparent reason, I thought reverting back to factory setting (Reset Phone) will do - but that's another issue. So, I opt for Reset Phone and all that, then come to realize when I glanced thru "Extras + Info" under Settings and bam.. LUMIA DENIM!... I mean, i thought for us TMo customers or perhaps the vast majority of carriers wouldn't even expect Denim for early Q1 2015. Maybe I was wrong?..