I have this issue too. I disabled HD Voice under networks and noticed an improvement.
Sent from my SAMSUNG-SM-N910A using XDA Free mobile app
I got mine today and it's a refurb from late 2013. Was referbed 5/2014 according to the sticker. Signal rocks and I get signal where I never had it before and better than my wife's Moto X. Came with NC4 but already rooted and debloated. Love my ph...