The pcap file shows that OsmoBSC is sending SABME requests but that the BTS never responds to any of them. I would assume that somehow the timeslot configuration on BTS and BSC side don't agree, i.e. you're sending the SABME on a timeslot that the BTS doesn't expect it on.
I remember that the E1 related configuration on the Noika BTS (at least the InSite) is relatively complex. Might be best to check all related settings.