'Add a <Sip> element
:param uri: sip url
:param username: sip username
:param password: sip password
:param url: action URL
:param method: action URL method
:param status_callback_event: events to call status callback
:param status_callback: status callback URL
:param status_callback_method: status callback URL method
:param kwargs: additional attributes
:return: <Dial> element'

def sip(self, uri, username=None, password=None, url=None, method=None, status_callback_event=None, status_callback=None, status_callback_method=None, **kwargs):

    return self.nest(Sip(uri, username=username, password=password, url=url, method=method, status_callback_event=status_callback_event, status_callback=status_callback, status_callback_method=status_callback_method, **kwargs))
