Few days ago, I came across a situation where I had to get data from a .NET Web Service using jQuery Ajax. Here is a sample code:

var soapMessage =
    '<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>'+
            '<SomeMethod>'+
                '<Arg1>Arg1 Value</Arg1>'+
                '<Arg2>Arg2 Value</Arg2>'+
            '</SomeMethod>'+
        '</soap:Body>'+
    '</soap:Envelope>';

$.ajax({
    url: "http://localhost/someService.svc",
    type: "POST",
    dataType: "xml",
    contentType: "text/xml; charset=\"utf-8\"",
    headers: {
        SOAPAction: "http://localhost/someService/SomeMethod"
    },
    data: soapMessage,
    success: function(soapResponse){
        //DO SOMETHING
    }
});