global method: doHTTPRequest

when using this global method to send http request (I used it to send SMS), the message is sent successfully, but I see the following error:
Error calling method: doHttpRequest in class: com/hp/ov/sm/server/utility/HttpClient Exception (java.io.IOException: Server returned HTTP response code: 500 for URL: https://soa.holymakkah.gov.sa/REST/NETWORK_SMS_SEND?Recipient=0541646297&SMS=INeedTestIt&Username=hpsm&Password=****&Sender=HPSM) at char 1
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I call a rule set that run the following javascript
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function SendSMS()
{
var url = "https://soa.holymakkah.gov.sa/REST/NETWORK_SMS_SEND?Recipient=0541646297&SMS=I Need Test It&Username=hpsm&Password=****&Sender=HPSM";
var headers = new Array();
var SMSrequest;
var reply;
var respHeaders = new Object();
SMSrequest = doHTTPRequest( "GET", url, headers, null, 10, 10, null, respHeaders );
}
SendSMS();
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Also note I have tried to change the headers but no luck.

Also this method is used in other applications successfully.

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Environment specifications:
SM APP: 9.41
SM Serv: 9.41
SM Webtier: 9.41
SM DB: SQL 2012
SM OS: Windows Server 2012 R2