Iphone help

[HORNINTHEUSA]

My ringer volume is turned up all the way. When I go to settings I can hear my choice of ring tones. But when I have an incoming call, I HEAR NOTHING. Is there a mute button or something I don't know about? Thanks in advance

 

[HORNINTHEUSA]

Never mind. Found it myself. There is a mute button that I could not see because of my Otterbox