Send A Callback To Other Page?

I have an asp.net page. I'm using a jquery library to open a modal window on link click. Within this modal window I'm loading another page. After i make update within this modal window I need to send a callback to "Parent" page. if I call function from this window I'm getting the error it couldn't find function. Window.opener.functionname also not working.

here is an example of my code

$(function () {
$('#ControlId').click(function (e) {
e.preventDefault();
$.ModalWindow({
bgColor: '#3333cc',
url: 'default.aspx'
});
return false;
});
return false;
});
});

Is there any way how to send a callback?