Phone goes from vibrate to full volume after I receive a phone call

I put my phone on vibrate during work so I don't get interrupted. Recently, when I get phone calls, after the call goes through, my phone goes from silent to full volume ring all its own. Happens when I make phone calls as well. What could be causing this?

from DroidForums.net | Android Forums & News http://ift.tt/2jmNOvF
via IFTTT