Im in the UK & have a S4 i9505 my plan is 4G, in network settings I had auto connect (4G,3G,2G) based on this i was only getting 1 bar if not no bars everywhere, i was concerned because I thought I had signal issues, however I spoke to Samsung & because I had it on 4G,3G,2G it was seaching for 4G 1st and because 4G is new in my area & low signal that is why I was having the issues, as soon as I changed my network settings to 3G/2G only my signal has improved & working, so for people having poor signal go to network settings & change it to auto connect at 2G/3G if your phone is still having issues it may be the phone, but it fixed my issue. maybe that is why alot of people are having low signal if its on 4G/3G/2G i think Samsung should have made customers aware.