jQuery cross domain ajax call - Interpreted as script but transferred with MIME type text/xml

Trying to make a REST web service call using an ajax call. Whenever I try to run it, I receive the error, Interpreted as script but transferred with MIME type text/xml. Here's my code ("website" is actual website where web service is):

    <script src="http://ift.tt/1oMJErh"></script>
    <script type="text/javascript">

        function testCall() {
            var webMethod = "website";
            var un = 'un'
            var pw = 'pw'
            var parameters = "username=un&password=pw&change_ticket_number=CRQ000000011334&restuser=TEMPESP&restpass=restpw";

            $.ajax({
                url: webMethod,
                type: 'Post',
                data: parameters,
                crossDomain: true,
                username: un,
                password: pw,
                contentType: 'application/x-www-form-urlencoded; charset=utf-8',
                dataType: 'jsonp',
                success: function(data) {
                    alert('Success: ' + data);
                },
                error: function(errorThrown){
                    alert('Try again ' + errorThrown);
                }
            });
        }

I have been searching all over the web and this website for something like this but I haven't had any success.

I have initially had my dataType as "xml" as that's what the web services provdies but changed it to "jsonp" when I read about cross domain calls.

The parameters are what the web service is looking for. If I was to open an internet browser and put the url + parameters, it does show me the xml message.

I'm not sure how much control I have over the web service itself so my hope would be to figure out a way on how to translate this back to xml after jsonp successfully brings it over.

So the question remains, am I able to change my code in order to make this work, leaving the web service as is? If it's truly not possible, what needs to be done to the web service? Keeping in mind xml is being used.

Thank you for any help you can provide.