public static Task <dynamic> SavePhoneLink(PhoneLink phoneLink) { var taskCompletionSource = new TaskCompletionSource <dynamic>(); var request = new RestRequest("/v1/calendar/phone-link", Method.POST, DataFormat.Json); request.AddParameter("application/json", JsonConvert.SerializeObject(new { phoneNumber = phoneLink.PhoneNumber == "none" ? null : phoneLink.PhoneNumber, calendarId = phoneLink.CalendarId }), ParameterType.RequestBody); ApiClientHelper.Check(); ApiClientHelper.Client.ExecuteAsync <dynamic>(request, response => { ApiClientHelper.HandleException(response); taskCompletionSource.SetResult(null); }); return(taskCompletionSource.Task); }