Happy new year!:-)

Check out this link: https://github.com/ubports/dialer-app/issues/18 it will definitely help you.

I had faced same problem many time!

I recently bought one plus 5 and i must say this phone is awesome. and i want to that and i want to thanks this article http://www.techradar.com/reviews/oneplus-5 for helping me.

which vpn your are using