mobile

I have a d855 model and I read it can't use LTE. Mine displays H instead of LTE but streams hd video as fast as my LTE phone or at least I notice no difference. When I did speed test when tether to laptop I got 4mbps which is still high speed but I think LTE is way faster.

My question is if no 4g/LTE which is limited at 2.5gb per month then am I unlimited high speed ? Just slower high speed.