Hi @GPHA! If two way audio worked on another device, this is a good sign that your Video Doorbell is picking up and processing all audio. The best next step is to remove and reinstall the Ring app on your mobile devices, and ensure to accept all permissions. Please also check that bluetooth and any accessibility options on your mobile devices are disabled.
As long as the Ring app is up to date, wifi signal is sufficient, and the two way audio green answer button is being pressed during live view, two way audio should be working as intended. Feel free to let us know how this goes!