public CommandResponse hangup(String callId) {
		CommandResponse retVal = null;
		try {
			MultivaluedMap<String, String> queryParams = new MultivaluedMapImpl();
			queryParams.add(HangupParams.CALL_ID, callId);
			ClientResponse response = service.queryParams(queryParams)
					.path(HANGUP_RESOURCE).accept(MediaType.APPLICATION_JSON)
					.get(ClientResponse.class);
			if (response.getStatus() == 200) {
				retVal = instantiateCommandResponeFromJson(response);
			} else {
				retVal = new CommandResponse();
				retVal.setCallId(callId);
				retVal.setStatus(-10);
				retVal.setErrorMsg("Failed : HTTP error code : "
						+ response.getStatus());
			}
		} catch (Exception e) {
			retVal = new CommandResponse();
			retVal.setCallId(callId);
			retVal.setStatus(-20);
			retVal.setErrorMsg("Failed with exception: " + e.getMessage());
		}
		return retVal;
	}