Not reliable and getting worse

Update... It has become a bit better since my original review below but there is still much work to do. It still shuts down and crashes after going between WiFi and LTE so its not reliable to receive calls. The audio will go out on calls. Please get these things fixed. It is behaving the same on my IPad on both IOS 8-9. End of my update, original review below... I hate to give this review because I believe that out of all of the VoIP apps, Zoiper has the most potential. I have noticed that over the last year, the app has gone down hill in both stability and audio performance. Stability wise, I can never get the app to stay active so I miss 9 out of 10 calls because it crashes or shuts down in the background so everyone just goes to my voice mail. Its very frustrating for those trying to get ahold of me. Performance wise, it will ether lock up in between my connections going from WiFi and LTE and vice versa. Also, the audio is bad and people cant understand me about half of the time. When it works, it works great, the rest of the time, people say my audio ether cuts out completely or I sound like a robot. I have tried every codec and Im using the ultimate IOS device which is the IPad Air 2 aka IPad 6. Something needs to change.since the last 2 updates, there wasnt an update for a year prior. Please fix these issues.

Yoledone about Zoiper Premium voip soft phone