Call routing in OpenBSC Flow of events: # MO call initiated by MS, CHANNEL RQD, IMMEDIATE ASSIGN # MS sends CC SETUP message, we assume already on TCH/H FACCH # OpenBSC does a subscriber lookup based on the target extension * If a subscriber is found: # send CALL PROCEEDING message to MO # page the MT subscriber and ask itI to ask for TCH/H # once paging completes, we have the TCH/H for the MT end # send SETUP to MT # receive CALL CONFIRMED from MT # set-up the TRAU mux mapping between the E1 subslots for both TCH/H # receive ALERTING from MT, route ALERTING to MO # receive CONNECT from MT, confirm to MT with CONNECT_ACK # send a CONNECT message to MO, receive CONNECT_ACK from MO * If subscriber is not found: # send RELEASE COMPLETE with apropriate cause to MO (1: unalloacated 3: no route) Thoughts about RR/MM: * we allocate RR/MM entities on demand, when we need them