Viber/BT SmartTalk apps perform very poor

[afgzee]

Apps like Viber and BT SmartTalk perform really poorly on my HTC One. Viber constantly cuts out or people sound like a robot when I am talking to them, and warns of poor call quality, same happens with BT SmartTalk, this only happens when I put the phone on my face near my eye to hear what someone is saying. Its very frustrating.

Does this happen to anyone else and how do I get this fixed?

 

[afgzee]

I've noticed whether on data or wifi, it seems to get switched off too and re-establish a connection, this may have something to do with it?