It would be interesting to know if others, who are using this app have a different make and model phone other than Google phone. I have OnePlus 8 Android phone, and there seems to be conflict in using Phone by Google dialer app. I am not given the option to select RTT or Voicemail, when dialing a number. It auto selects RTT. I have selected RTT Always Visible(Manual) selected. So, it should give me the two options... either select RTT or Voice call.