code: public String getCallId() {
  		if(this.sessionCreatingDialog != null)
  			return this.sessionCreatingDialog.getCallId().getCallId();
  		else if(sessionCreatingTransactionRequest != null)
  			return ((CallIdHeader)this.sessionCreatingTransactionRequest.getMessage().getHeader(CallIdHeader.NAME)).getCallId();
  		else if(key != null)
  			return key.getCallId();
  		else
  			return null;
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.sip.SipSession#getCallId()