Originally Posted by peterposh
My s4 has taken to dropping out mid call when on bluetooth calls in the car, I know iit's not the car as it happens in all three of my vehicles, it doesn't drop call just drops back to the handset, also when I use the speaker on the phone that only goes for a minute or so until it drops to ear speaker
You do not say which model of S4 you have or which firmware you are on. See #1.2
of 18 Galaxy S4 models - know yours?
If you are on Android 4.3, then this is a known firmware issue that is fixed in the latest release...
Android 4.3 firmware release fixes bugs