It's set to call everyone with RTT and thinks I can't hear!!! How do I turn that off? I didn't turn it on. Thank you developer for telling me what RTT is and how to use it, but this phone app still makes RTT calls by default. Then I have to manually change the call over to voice. When people called me it was answering with RTT. So I figured out this is not the app that came with my phone and deleted it. The other phone app (also called Phone) seems to work normally.