Another test in Poland. As of today UM+ (outgoing calls) doesn't work with Era - the callback connection is broken after one second ringing or no ringing occurs at all. After the failed callback, the first the message "Calling" followed by number dialed dispalys for a few second and the whole thing ends with "Service unavailable" message and a single "OK" option to close that message.
Caller ID is rather unstable both ways and more often it doesn't display.
Edit:
SMSes from Era to UM+ don't go through. I said before that they went OK but I realised that I had forgotten to test the Era->UM+
case. So the conclusion is that UM+ roaming on Era network works for incoming calls/SMSes only
