If you don't receive sound for incoming calls/texts, please try to verify the following:
On your iDevice settings, please make sure that the Talkatone app is under Notifications, and the Allow Notifications feature is ON. Please make sure all buttons are enabled. (see video Tutorial below)
If this doesn't help. Please check your volume settings on the device itself.
When on Talkatone, try the buttons on the side of your device, this should work.
If you are using an iPad make sure it is not muted. Please follow this link (http://support.apple.com/kb/HT4085) to Apple's support pages for instructions on how to fix this.
Alternatively try deleting the app and reinstalling it again and restart your device.
Allow Notifications (http://goo.gl/Nu5Jyc)