I'm still trying to figure out what's going wrong with the concatenation = true. It doesn't work for text or binary, for the current snapshot. I notice two interesting things: in access.log there is dump of each message sent out, plus udh header. However I note that in each case, the reported length is one greater than should be. For instance for the udh it reports a length of 6, the message a length of 153. Is this part of the problem?
Help! Thanks. Paul.