while(it.hasNext()) {
SipcRequest request = it.next();
ResponseHandler handler = request.getResponseHandler();
if(handler!=null) {
if(ex==null){
handler.timeout(request);
}else if(ex instanceof TransferException){
handler.ioerror(request);
}else if(ex instanceof SystemException){
handler.syserror(request, ex.getCause());
}else{