code: public SipSession getSipSession(String id) {
  		if(!isValid()) {
  			throw new IllegalStateException("SipApplicationSession already invalidated !");
  		}
  		if(logger.isDebugEnabled()) {
  			logger.debug("Trying to find a session with the id " + id);
  			dumpSipSessions();
  		}
  		boolean isPresent = false;
  		SipSessionKey sipSessionKey = null;
  		try {
  			sipSessionKey = SessionManagerUtil.parseSipSessionKey(id);
  			isPresent = sipSessions.contains(sipSessionKey);
  		} catch (ParseException e) {
  			//can happen if the id passed is invalid
  		}
  		if(isPresent) {
  			return sipContext.getSipManager().getSipSession(sipSessionKey, false, null, this).getFacade();
  		} else {
  			return null;
  		}
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.sip.SipApplicationSession#getSipSession(java.lang.String)