I am using an Unlocked Samsung Galaxy s4. Model SGH-1337M. It was working completly fine on Android 4.3. But since i updated it to Android 4.4.2 last month I have been experiencing network issues. I am not sure if this problem is phone related or network related. I contacted samsung and they said they havnt recieved this complaint from anyone and said to try to change SIM cards. I experiencex some other laggs and bugs when i initially updated to 4.4.2 but those were eliminated after i performed a factory reset on the device. Only the connectivity issue remains. I will describe the issue in detail below. When the phone is sleeping sometimes the network bars on the phone go to zero and the phone doesnt notify of having 0 bars or no connection but it seems as if the phone thinks there is network but calling/texting doesnt work. even when i go into settings to search for network it just stays frozen and also if i try changing network mode the settings dont change anything. The only solution that works is that i restart my device and i get the network bars again. There is no specific region this happens at. This is giving me major problems because I dont know when there is network and when there isnt unless i wake up the phone and check if there are barsm So i cant gurantee myself to recieve calls or texts while the phone is sleeping without verifying it every time. Has anyone else experienced this problem? What can I do to fix it? Any help is appreciated. I can show a screenshot of how the network bars are 0 if needed.