I recently switch carriers and got a used Galaxy S4 to replace the one I would no longer be using. The phone was already cleaned up but I did a factory reset on it myself to be sure. The problem I have is that one or more times during a call the phone vibrates and/or beeps as though it has a notification for me. When I check the notifications (during or after the call) there are none.
This happens almost every call, and within about the first 1-2 minutes of the call, but it is not at a consistent time. I am not getting these phantom notifications any other time, just when on a call. I'm not a very heavy caller, so I don't know when this started, but it has been doing it for more than a month at least.
It will happen even immediately after rebooting the phone and occurs whether using the handset or the wired headset (don't recall if I've tried it with BT). I have disabled all in-call alerts in the settings (including roaming, data, and connection alerts) and every notification option I can find within apps (excepting the ones I need) but to no avail.
Is there any way to disable this, or at least to determine what is causing the false notifications?
Additional info:
Carrier: Sprint Phone Model: SPH-L720 Android Version: 4.4.2 Rooted: YES ROM: Stock from carrier (Samsung Touchwiz)