You can restart the application by following these instructions:
For Android Users:
Tap on the Quit option under Talkatone settings (open Talkatone Settings by tapping on the Android menu button). You will find the Quit option at the very end of the options list on the screen.
For iOS users:
Double-click the home button, then SWIPE UP on the mini-window of Talkatone.
To restart Talkatone tap on the Talkatone Icon on your device.