public async Task <ActionResult> start([FromBody] PhoneVerificationRequestModel verificationRequest)
        {
            HttpContext.Session.Set <PhoneVerificationRequestModel>("phone_verification_request", verificationRequest);

            if (ModelState.IsValid)
            {
                string result;
                if (verificationRequest.via == Verification.SMS)
                {
                    result = await authy.phoneVerificationRequestAsync(
                        verificationRequest.CountryCode,
                        verificationRequest.PhoneNumber
                        );
                }
                else
                {
                    result = await authy.phoneVerificationCallRequestAsync(
                        verificationRequest.CountryCode,
                        verificationRequest.PhoneNumber
                        );
                }
                return(Ok(result));
            }
            else
            {
                return(BadRequest(ModelState));
            }
        }
        public async Task <ActionResult> voice()
        {
            var currentUser = await userManager.GetUserAsync(this.User);

            var result = await authy.phoneVerificationCallRequestAsync(
                currentUser.CountryCode,
                currentUser.PhoneNumber
                );

            return(Ok(result));
        }