protected async void SendSms_Click(object sender, EventArgs e) { var cid = Request.QueryString["cid"]; CustomerModel customer = new CustomerModel(Convert.ToInt32(cid)); string customerPhone = customer.phonNumber; string customername = customer.firstnmae + " " + customer.lastname; string teratmentID = Request.QueryString["tid"].ToString(); RepairJobl repairJob = new RepairJobl(Convert.ToInt32(teratmentID)); string LicensePlate = repairJob.license_Number; Garge garge = new Garge(Convert.ToInt32(Session["UserID"])); string garageName = garge.GetNameGarga(); string garageNumber = garge.GetPhone(); //This Method Sends Using API and its ASYNC (You have to wait until the process ends) await SmsSender.SendUsingAPIAsync( garageNumber, garageName, customerPhone, customername, LicensePlate ); Thread.Sleep(5000); //Sleep for 5 SECOND Until API FINISH His Work showmodel(); }