OK guys here is the FIX it works for me every time (for the 5C) Look at where your proximity sensor will sit on the inside of the screen, take a screwdriver or something with a pointy tip and scratch the paint off this little area making it clear or see through.(NOTICE:ONLY SCRATCH OFF THE PAINT WHERE THE PROXIMITY SENSOR TOUCHES THE SCREEN) Put it back together and test by making a call if it didn't work you need to replace your front camera flex. feel free to ask any ?