// Create the Subscription request to register with the presence agent and receive notifications.
configuration.setCallIdHeader(provider.getNewCallId());
Request request = configuration.createSipRequest(1, Request.SUBSCRIBE, configuration.getEventHeaderName());
// Create the subscriber transaction from request.
ClientTransaction subscriberTransactionId = provider.getNewClientTransaction(request);
// Add an Event header for the subscription.
request.addHeader(configuration.getEventHeader());
subscriberDialog = subscriberTransactionId.getDialog();
// Send the outgoing subscription request.
subscriberTransactionId.sendRequest();
}