Cellular Network Infrastructure » Radio Access Network » OsmoBTS

3GPP TS 48.058 Section 8.1 states:

In the uplink direction (messages from MS), all messages received in I- frames and all messages received in UI-frames
except for the MEASurement REPort message are considered as transparent. They are forwarded to BSC as DATA
INDication and UNIT DATA INDication messages respectively.

So an ESTABLISH INDICATION is clearly not covered by the above and hence non-transparent. Still, OsmoBTS is sending it as "transparent".

This was found (once again) by our TTCN-3 tests, as there the receive template for RLL_EST_IND matches only when the transparent bit is set correctly.