function refCatastral()
{
    var wsUrl = "http://ovc.catastro.meh.es/ovcservweb/OVCSWLocalizacionRC/OVCCallejero.asmx";


    var soapRequest =
'<?xml version="1.0" encoding="utf-8"?>'+
'<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"'+
    'xmlns:xsd="http://www.w3.org/2001/XMLSchema"'+
    'xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">'+
  '<soap:Body>'+
    '<Provincia xmlns="http://www.catastro.meh.es/">Madrid</Provincia>'+
    '<Municipio xmlns="http://www.catastro.meh.es/">Madrid</Municipio>'+
    '<RefCat xmlns="http://www.catastro.meh.es/">1749101VK4714H0001KW</RefCat>'+
  '</soap:Body>'+
'</soap:Envelope>';

    $.ajax({
        type: "POST",
        url: wsUrl,
        contentType: "text/xml; charset=\"utf-8\"",
        dataType: "xml",
        data: soapRequest,
        success: processSuccess,
        error: processError
    });
    alert(soapRequest);
}

function processSuccess(data, status, req) {
    alert(req);
}

function processError(data, status, req) {
    alert(req.responseText + " " + status);
}