Re: Speakerphone turns off during calls
I had the same issue with my new Sprint Samsung Galaxy S4 (model # SPH-L720, running Android 4.2.2), which I've had for less than 16 days. When a call connected using either the speakerphone or a Bluetooth device, within 2-5 minutes the call audio would drop back to the handset earpiece, even though the speakerphone indicator (or Bluetooth call audio indicator) would still be showing green (connected). I also had chronic problems with the call terminating on the initial call (within a second of connecting) when connected to a Bluetooth device. Once I deinstalled Viber the problems ceased occurring.
FYI, I did contact Samsung support. They had me put the phone in Safe Mode by powering down the handset, then powering it back up and holding down the Volume Down button for several seconds as soon as you see the Samsung Logo (NOT holding down Volume Down button and Power Button at the same time), I also pulled out the external 32GB micro SD card too. At the lock screen you will see the words "safe mode" displayed in the lower left-hand corner. When I was in this mode the speakerphone and Bluetooth problems were not evident. Samsung said that this is a good indication that it was an app causing the problems. So glad I did this, instead of following Sprint's advice to return the phone to Radio Shack (where I purchased it recently) for an exchange! Would have been a huge waste of time...