Why does the in-call volume change on its own on my Samsung Galaxy S3? I have a Samsung Galaxy S3 (SCH-I535) running Android 4.4.2 and I'm having an extremely annoying issue: Whenever I make or receive a call, if I adjust the in-call volume to the desired level (usually somewhere between 80% - 100% if I am in a noisy place) then during the call, the call volume will suddenly drop to roughly 25% - 35%

This happens repeatedly during a call. I am not using a headset of any kind: I am simply holding the phone up to my ear. I am positive that I am not pressing any buttons on the side of the phone, and I press the lock button to turn the screen off before holding the phone up to my face, so I'm sure I'm not triggering any on-screen functions with my cheek/ear.

This makes it doubly annoying because the volume buttons don't appear to work reliably when the phone is in this state. So after a few minutes at the desired volume, suddenly I can't hear he other party and I need to ask them to please wait, bring the phone away from my face, unlock the screen, adjust the volume back to maximum using the volume buttons (ever time I see the volume slider has dropped from where I last had it set) lock the screen again and then resume my call.

This will happen repeatedly, every few minutes while on a call.

I have the stock Verizon/Samsumg OS, phone is not rooted, and I can't find any setting which might be causing this. I don't have any custom volume adjustment apps installed. Looking for any assistance! Why does the in-call volume drop on it's own on my Samsung Galaxy S3?
The problem was caused by an app that I installed for allowing the company I work for to page me. This proprietary app had a bug that caused it to drop the in-call volume during a call; Updating the app fixed the problem.