code: def sip(self, sip_url, username=None, password=None, url=None, method=None,
              status_callback_event=None, status_callback=None,
              status_callback_method=None, **kwargs):
          
          return self.nest(Sip(
              sip_url,
              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
          ))
docs: Create a <Sip> element
  
          :param sip_url: SIP URL
          :param username: SIP Username
          :param password: SIP Password
          :param url: Action URL
          :param method: Action URL method
          :param status_callback_event: Status callback events
          :param status_callback: Status callback URL
          :param status_callback_method: Status callback URL method
          :param kwargs: additional attributes
  
          :returns: <Sip> element