MIM 2016 OTP SMS Unable to send security code

The error page was displayed to the user.
Details:
Title: Unable to send security code
Message: Unable to send a security code. Please contact your help desk for assistance.
Source: 
Attributes: 
Details: Microsoft.IdentityManagement.CredentialManagement.Portal.Exceptions.OneTimePasswordDeliveryException: ValidationError:UnableToSendSecurityCode ---> System.ServiceModel.FaultException: ValidationError:UnableToSendSecurityCode
   at Microsoft.ResourceManagement.WebServices.SecurityTokenServiceClient.RequestSecurityTokenResponse(Message request)
   at Microsoft.ResourceManagement.WebServices.SecurityTokenServiceClient.RequestSecurityTokenResponse(RequestSecurityTokenResponseType request, ClientOptionsHelper clientOptionsHelper, MessageBuffer& messageBuffer)
   at Microsoft.ResourceManagement.WebServices.Client.AuthenticationRequiredException.Authenticate(AuthenticationChallengeResponseType[] authenticationChallengeResponses, MessageBuffer& messageBuffer, ClientOptionsHelper clientOptionsHelper)
   at Microsoft.IdentityManagement.CredentialManagement.Portal.Common.ResetProxy.GetChallenge(String domain, String userName, ChallengeContext gateChallengeResponse)
   at Microsoft.IdentityManagement.CredentialManagement.Portal.Common.ResetProxy.GetNextChallenge(String domain, String userName, ChallengeContext gateChallengeResponse, FaultExceptionHandlerDelegate faultExceptionHandler)
   --- End of inner exception stack trace ---
   at Microsoft.IdentityManagement.CredentialManagement.Portal.Common.ResetProxy.GetNextChallenge(String domain, String userName, ChallengeContext gateChallengeResponse, FaultExceptionHandlerDelegate faultExceptionHandler)
   at Microsoft.IdentityManagement.CredentialManagement.Portal.Components.DriverBase.GetNextGate(IGateControl currentGate)
   at Microsoft.IdentityManagement.CredentialManagement.Portal.Reset.Next()
   at System.Web.UI.WebControls.Button.OnClick(EventArgs e)
   at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument)
   at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
CorrelationId: 
RequestId: 
ErrorCode: 3013

this is the error from event viewer , i tired to edit SmsServiceProvider.dll many time but without any success , this is last edit for SmsServiceProvider.dll

//------------------------------------------------------------
// Copyright (c) Microsoft Corporation.  All rights reserved.
//------------------------------------------------------------
namespace Microsoft.IdentityManagement.Samples
{
    using System;
    using System.Collections.Generic;
    using System.Globalization;
    using System.Net;
    using System.Text;
    using Microsoft.IdentityManagement.SmsServiceProvider;
    using System.Web;
    using System.Security.Cryptography;
    using System.IO;



    public class SmsServiceProvider : ISmsServiceProvider
    {

        public void SendSms(string mobileNumber,
                            string message,
                            Guid requestId,
                            Dictionary<string, object> deliveryAttributes)
        {
            mySMSProvider.SendSms(mobileNumber, message);
        }
    }


    class mySMSProvider
    {
        static string RequestURL = "http://XXX/httpSendSMS/Default.aspx";

        mySMSProvider()
        {
        }

        public static int SendSms(string userMobileNumber, string message)
        {
            WebClient wc = new WebClient();
            string requestData;

            requestData = Microsoft.IdentityManagement.Samples.mySMSProvider.GetRequestData(userMobileNumber, message);

            byte[] postData = Encoding.ASCII.GetBytes(requestData);

            byte[] response = wc.UploadData(mySMSProvider.RequestURL, postData);

            string result = Encoding.ASCII.GetString(response);  // result contains the error text

            int returnValue = System.Convert.ToInt32(result.Substring(0, 4), NumberFormatInfo.InvariantInfo);
            return returnValue;
        }

        public static string GetRequestData(string mobilePhone, string message)
        {

            string myrequestData;

            myrequestData = "UserName=" + "XX"
                 + "&Password=" + System.Web.HttpUtility.UrlEncode("XX")
                 + "&MobileNo=" + System.Web.HttpUtility.UrlEncode(mobilePhone)
                 + "&Language=" + System.Web.HttpUtility.UrlEncode("EN")
                 + "&MessageID=" + System.Web.HttpUtility.UrlEncode("ITNOC005")
                 + "&Varibales=" + System.Web.HttpUtility.UrlEncode(message)
                 + "&DelimiterChr=" + System.Web.HttpUtility.UrlEncode("+");

            return myrequestData;


        }
    };
}
 when you try to but http parameter on IE sms send success ,please any help ??