Ajax Web Service Call - No 'Access-Control-Allow-Origin' header is present

I will prefer to just enable CORS than changing all your AJAX call.

Do you try to modified the web.config for the webservice to add the following line yet ?

<system.webServer>
    <httpProtocol>
        <customHeaders>

            <add name="Access-Control-Allow-Origin" value="*" />
        </customHeaders>
    </httpProtocol>

Check also this questions for if CORS / JSONP is better for you So, JSONP or CORS?