use skype. groove ip is high reliability for incoming calls, but low sound quality on cell service. lots of delay. talkatone is better sound, but lower reliability for uptime. even more delay. skype has amazing sound, as good as voice calls many times, but reliability is horrible right now (jb and skype dont play well right now, but it does work). best part is almost no added delay as compared to regular voice calls.
but even though skype doesnt stay connected and crashes often, the sound is so good its all you will want to use. cell calls are bad enough as it is, you dont need to be making them worse. skype is just $30/yr too, and if you want incoming calls on the skype app its another $60. but you can save that $60/yr if you use talkatone or grooveip for incoming calls. me, i pay for the incoming calls because i really do like having the best quality sound i can when im on the phone.