msc { hscale="4"; ms [label="MS"], mgw [label="MGW"], nitb [label="MSC"], emh [label="External MNCC Hdlr"]; |||; ... [label="Mobile Originated call handled via OsmoMSC, no RTP proxy, IPBTS and external MNCC Handler"]; |||; --- [label="User on A-side dials a MO call from his phone"]; ms <=> nitb [label="RF Channel Establishment"]; ...; # MS sends CC SETUP, deliver it to MNCC ms -> nitb [label="CC SETUP [MSISDN]"]; nitb rbox nitb [label="CSTATE_INITIATED"]; nitb -> emh [label="MNCC-SETUP.ind [CALLING, BEARER_CAP, FACILITY, CALLED, USERUSER, SSVERSION, CCCAP"]; emh rbox emh [label="1 CALL_INIT"]; ...; --- [label="Exact time of RTP-CREATE up to Ext MNCC Hdlr"]; nitb <- emh [label="MNCC_RTP_CREATE[.req]"]; mgw <- nitb [label="MGCP CRCX"]; mgw -> nitb [label="MGCP CRCX ACK (MGW-IP, MGW-PORT)"]; nitb -> emh [label="MNCC_RTP_CREATE[.cnf] (MGW-IP, MGW-PORT)"]; ...; nitb <- emh [label="MNCC-CALL-PROC.req [BEARER_CAP, FACILITY, PROGRESS]"]; emh rbox emh [label="3 MO_CALL_PROC"]; nitb rbox nitb [label="CSTATE_MO_CALL_PROC"]; ms <- nitb [label="CC CALL PROCEDING"]; ...; # optional --- [label="Optional PROGRESS, can happen 0-N times"]; nitb <- emh [label="MNCC-PROGRESS.req [USERUSER]"]; emh rbox emh [label="3 MO_CALL_PROC"]; ms <- nitb [label="CC PROCEDING"]; ...; # optional --- [label="Optional; Indicates when B-side is ringing"]; nitb <- emh [label="MNCC-ALERT.req [FACILITY, PROGRESS, USERUSER]"]; emh rbox emh [label="4 CALL_DELIVERED"]; nitb rbox nitb [label="CSTATE_CALL_DELIVERED"]; ms <- nitb [label="CC ALERTING"]; ...; # ask the MGW to connect its RTP stream to the given IP+PORT --- [label="Exact time of RTP-CONNECT up to Ext MNCC Hdlr"]; nitb <- emh [label="MNCC_RTP_CONNECT[.req] (EMH-IP, EMH-PORT)"]; mgw <- nitb [label="MGCP MDCX (EMH-IP, EMH-PORT)"]; mgw -> nitb [label="MGCP MDCX ACK"]; nitb -> emh [label="MNCC_RTP_CONNECT[.cnf] (MGW-IP, MGW-PORT)"]; ...; --- [label="User on B-side answers the call"]; nitb <- emh [label="MNCC-SETUP.rsp [FACILITY, PROGRERSS, CONNETED, USERUSER]"]; emh rbox emh [label="? CONNECT_INDICATION"]; nitb rbox nitb [label="CSTATE_CONNECT_IND"]; ms <- nitb [label="CC CONNECT"]; ...; ms -> nitb [label="CC CONNECT ACK"]; nitb rbox nitb [label="CSTATE_ACTIVE"]; nitb -> emh [label="MNCC-SETUP-COMPL.ind"]; emh rbox emh [label="10 ACTIVE"]; ...; ...; ...; --- [label="User on A-side hangs up the call"]; ms -> nitb [label="CC DISCONNECT"]; nitb rbox nitb [label="CSTATE_DISCONNET_REQ"]; nitb -> emh [label="MNCC-DISC.ind [CAUSE, FACILITY, USERUSER, SSVERSION]"]; emh rbox emh [label="12 DISCONNET_IND"]; ...; nitb <- emh [label="MNCC-RELEASE.req [CAUSE, FACILITY, USERUSER]"]; emh rbox emh [label="19 RELEASE_REQ"]; nitb rbox nitb [label="CSTATE_RELEASE_REQ"]; ms <- nitb [label="CC RELEASE"]; ...; ms -> nitb [label="CC RELEASE COMPLETE"]; nitb -> emh [label="MNCC-RELEASE.cnf [CAUSE, FACILITY, USERUSER, SSVERSION]"]; ...; ms <=> nitb [label="RF Channel Release"]; ...; }