sb.append(msg.getCallIdHeader().getCallId());
sb.append(msg.getRequestLine().getAddress().toString());
sb.append(msg.getCSeqHeader().getSequenceNumber());
MultipleHeader rr=msg.getRoutes();
if (rr!=null) sb.append(rr.size());
return (new SimpleDigest(7,sb.toString())).asHex();
}