gistfile1.java

@Override
public void processResponse(ResponseEvent arg0) {
	Response response = (Response) arg0.getResponse();
	ClientTransaction tid = arg0.getClientTransaction();
	System.out.println(response.getStatusCode());
	if (response.getStatusCode() == Response.PROXY_AUTHENTICATION_REQUIRED
			|| response.getStatusCode() == Response.UNAUTHORIZED) {
		AuthenticationHelper authenticationHelper = ((SipStackExt) sipStack)
				.getAuthenticationHelper(new AccountManagerImpl(),
						headerFactory);
		try {
			ClientTransaction inviteTid = authenticationHelper
					.handleChallenge(response, tid, sipProvider, 5);
			inviteTid.sendRequest();
		} catch (NullPointerException e) {
			e.printStackTrace();
		} catch (SipException e) {
			e.printStackTrace();
		}
}