Can't find PhoneAuthProvider class using Firebase with Xamarin in Xamarin.Firebase.Auth

I'm am using Xamarin.Firebase.Auth https://www.nuget.org/packages/Xamarin.Firebase.Auth/ latest version

I want to use Firebase Phone Authentication and require the PhoneAuthProvider class but I can't seem to find it under Firebase.Auth.
Just to mention only PhoneAuthProvider class is missing whereas I can see the TwitterAuthProvider EmailAuthProvider etc.

What option do I have, I require phone authentication with Firebase on Xamarin
Thanks