// Both 2xx response to SUBSCRIBE and NOTIFY need a Contact
response.addHeader(sipPresenceAgent.getConfiguration().getContactHeader());
// Expires header is mandatory in 2xx responses to SUBSCRIBE
response.addHeader(sipPresenceAgent.getConfiguration().getExpiresHeader());
st.sendResponse(response);
LOG.debug("SipPresenceAgentListener: Sent OK Message");
LOG.debug("SipPresenceAgentListener response: {}", response);
sendNotification(eventHeader, isInitial, request.getContent());