public async Task <IActionResult> PostAsync(string phoneNumber)
        {
            string     sessionID = string.Empty;
            OTPService service   = new OTPService();
            var        response  = await service.GenerateOTPAsync("username", "password", "url", phoneNumber);

            //check sessionID value
            if (true)
            {
                return(Ok(sessionID));
            }
            else
            {
                return(BadRequest());
            }
        }