IMHO it would be something like that:
For basic call CC-tracing:
SETUP
DISCONNECT
RELEASE
ALERTING
CALL CONFIRMED
CALL PROCEEDING
CONNECT
CONNECT ACKNOWLEDGE
EMERGENCY SETUP
RELEASE COMPLETE
Less useful:
START_DTMF
STOP_DTMF
STOP_DTMF_ACKNOWLEDGE
START_DTMF_ACKNOWLEDGE
START_DTMF_REJECT
STATUS
STATUS_ENQUIRY
FACILITY
HOLD
HOLD_ACKNOWLEDGE
HOLD_REJECT
RETRIEVE
RETRIEVE_ACKNOWLEDGE
RETRIEVE_REJECT
Rare:
PROGRESS
CC_ESTABLISHMENT
CC_ESTABLISHMENT_CONFIRMED
RECALL
START_CC
MODIFY
MODIFY_COMPLETE
MODIFY_REJECT
USER_INFORMATION
CONGESTION_CONTROL
NOTIFY