As title implies, I know the L920 supports HD Voice, but of late, my L920 doesn't seem to do it no more since the Amber update. I'm in a good 3g+ or H+ signal area on T-Mobile(not 4g). Phoned T-Mobile and they said it only works under 4g. The other parties I phone also have HD enabled Handsets, one use 4g, all the others use 3g. Does anyone else find this?