public async Task<JsonResult> CallOut(string number, string conferenceId) { try { var factory = new WebApiClientFactory().CreateClient<ICalloutApiEndpoints>("https://api.sinch.com", new ApplicationSigningFilter(appKey, Convert.FromBase64String(appSecret)), new RestReplyFilter()); number = number.StartsWith("+") ? number.Trim() : "+" + number.Trim(); var result = await factory.AddParticipant(new CalloutRequest { method = "conferenceCallout", conferenceCallout = new ConferenceCallout { cli = "+17864088194", destination = new Destination {endpoint = number, type = "number"}, domain = "pstn", conferenceId = conferenceId, greeting ="Welcome to the conference", enableDice = true, enableAce=true, } }); Debug.WriteLine(result.callId); return Json(null, JsonRequestBehavior.AllowGet); } catch (Exception e) { Debug.WriteLine(e.Message); } return Json(null, JsonRequestBehavior.AllowGet); }