public void StartVerification(string phoneNumber)
        {
            authType = AuthType.Phone;

            var options = new PhoneAuthOptions
                          .Builder(FirebaseAuth.Instance)
                          .SetPhoneNumber(phoneNumber)
                          .SetTimeout(Long.ValueOf(60), TimeUnit.Seconds)
                          .SetCallbacks(phoneCallback)
                          .SetActivity(Xamarin.Essentials.Platform.CurrentActivity)
                          .Build();

            PhoneAuthProvider.VerifyPhoneNumber(options);
            SetVerificationStatus(VerificationStatus.Initialized);
        }
        public void ResendVerificationCode(string phoneNumber)
        {
            authType = AuthType.Phone;

            var options = new PhoneAuthOptions
                          .Builder(FirebaseAuth.Instance)
                          .SetPhoneNumber(phoneNumber)
                          .SetTimeout(Long.ValueOf(60), TimeUnit.Seconds)
                          .SetCallbacks(phoneCallback)
                          .SetActivity(Xamarin.Essentials.Platform.CurrentActivity);

            if (ResendToken != null)
            {
                options.SetForceResendingToken(ResendToken);
            }

            PhoneAuthProvider.VerifyPhoneNumber(options.Build());
            SetVerificationStatus(VerificationStatus.Initialized);
        }