If you don't receive sound for incoming calls/texts, please try to verify the following:
On your device, go to Settings, tap on Application Manager, tap on Talkatone icon, and make sure to check the box next to the Show Notifications option (see video tutorial below).
Also, please make sure that all Volume Settings are adjusted all the way up. Change the volume with volume buttons on the side of the device.
Now, on Talkatone settings, tap on Call Settings, uncheck the box next to the Native Audio and make sure that the Audio Playback Stream option is set up for Voice Call.
While on Talkatone increase the audio (using the buttons on the side of your device).
Then restart the app and try again.
If this didn’t help, try deleting/reinstalling the app and restart your device.