Samsung S4/Sprint

The best and easiest way to fix this issue is to dump Sprint. I have been standing in the middle of an area on their coverage map that says they have 4G LTE and had the calls to them drop every 1.5 minutes. There will always be issues with them and their service. If it's not one thing, it's another as you are finding out. I was with them for a number of years before I finally wised up. Even with my corp. discount, it was not worth putting up with them any longer. I switched before other company's were paying your fees if you went with them. It cost me $1250 to switch and I haven't regretted it for a second. I have never had a dropped call and I have been able to use my phone as a wifi hotspot everywhere I have been. Sprint is famous for customer no-service and there are far too many companies to choose from these days to put up with poor service, poor network, as as you can now tell, fixes that aren't really fixes.