How to use type: "POST" in jsonp ajax call

You can't POST using JSONP...it simply doesn't work that way, it creates a <script> element to fetch data...which has to be a GET request. There's not much you can do besides posting to your own domain as a proxy which posts to the other...but user's not going to be able to do this directly and see a response though.

Use json in dataType and send like this:

    $.ajax({
        url: "your url which return json",
        type: "POST",
        crossDomain: true,
        data: data,
        dataType: "json",
        success:function(result){
            alert(JSON.stringify(result));
        },
        error:function(xhr,status,error){
            alert(status);
        }
    });

and put this lines in your server side file:

if PHP:

header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: POST');
header('Access-Control-Max-Age: 1000');

if java:

response.addHeader( "Access-Control-Allow-Origin", "*" ); 
response.addHeader( "Access-Control-Allow-Methods", "POST" ); 
response.addHeader( "Access-Control-Max-Age", "1000" );

Modern browsers allow cross-domain AJAX queries, it's called Cross-Origin Resource Sharing (see also this document for a shorter and more practical introduction), and recent versions of jQuery support it out of the box; you need a relatively recent browser version though (FF3.5+, IE8+, Safari 4+, Chrome4+; no Opera support AFAIK).

JsonP only works with type: GET,

More info (PHP) http://www.fbloggs.com/2010/07/09/how-to-access-cross-domain-data-with-ajax-using-jsonp-jquery-and-php/

.NET: http://www.west-wind.com/weblog/posts/2007/Jul/04/JSONP-for-crosssite-Callbacks