| Call routing in OpenBSC |
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| Flow of events: |
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| # 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) |
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| Thoughts about RR/MM: |
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| * we allocate RR/MM entities on demand, when we need them |