Whatsapp calls cutting outWatch
Even I faced the same kind of issue in my Android phone. That is the issue of internet connection. If you are having slow internet connection then either there will be call drop or you won't able to listen to the voice clearly.
I deleted the VPN profile and it made no difference. I tried switching off wifi and using 3G to connect and that helped a little bit but not much. I have an iPhone 6. It is so annoying. Is it my phone? or a Whatsapp problem? Or my internet connection which is not great but not bad and is pretty stable. Anyone can help?