Cross domain using Jquery

Hi am using the below script for calling a webservices..

<script language="javascript" src="/Style%20Library/Jquery/jquery-1.11.1.js" type="text/javascript"></script><script language="javascript" src="/Style%20Library/Jquery/jquery-1.11.1.min.js" type="text/javascript"></script><script language="javascript" src="/Style%20Library/Jquery/jquery.spservices-0.7.2.js" type="text/javascript"></script><script language="javascript" src="/Style%20Library/Jquery/jquery.spservices-0.7.2.js" type="text/javascript"></script><script type="text/javascript">

var firstURL;
var thisFirstName = $().SPServices.SPGetCurrentUser({
 fieldName: "FirstName",
 debug: false
});
var thisLastName = $().SPServices.SPGetCurrentUser({
 fieldName: "LastName",
 debug: false
});
var thisEmailID = $().SPServices.SPGetCurrentUser({
 fieldName: "Email",
 debug: false
});

alert(thisFirstName );
alert(thisLastName );

alert(thisEmailID );

firstURL = "site url with token";

alert(firstURL);

                $.ajax({
                        type: 'POST',
                        url: firstURL,                      
                        data: {},
                        dataType:'json',   -- if I put Json it is throwing cross domain issues and when I put jsonP then it is not working.
                        success:function(data)
{             

alert('success');
                                                                                                rcvtoken = JSON.stringify(data);
  secondURL = 'http://54.179.174.7/users/sign_in?token=' + rcvtoken.replace(/\"/g, "");
window.location.replace(secondURL);
},
                    error:function(jqXhr, textStatus)
{
                                                                                 alert('Unable to redirect to the EDGE Portal. Please contact your administrator - ' + JSON.stringify(jqXhr));
}                                                             
});</script>

need your help please.

Thanks & Regards

Rakesh