When the SETUP message is delivered on a broadcast data link, the network shall maintain a state machine that tracks the overall progression of the incoming call. The network shall also maintain an associated call state for each responding user as determined by the data link on which a message is received.
Upon receipt of the first CALL PROCEEDING message from a user (assuming no other user had previously responded with an ALERTING or CONNECT message when the SETUP message has been delivered on a broadcast data link), the network shall stop timer T303 (or, in the case of overlap receiving, timer T304 for that user); start timer T310, and enter the incoming CALL PROCEEDING state.
When the SETUP message has been delivered on a broadcast data link, the network shall (at a minimum) associate the incoming call proceeding state with each called user that sends a CALL PROCEEDING message as a first response to the broadcast SETUP message prior to expiration of timer T312. Actions to be taken when a user sends a first response to an incoming call after the expiration of timer T312 are described in 5.2.5.4. Timer T310 shall not be restarted.
Upon receipt of the first ALERTING message from a user (assuming no other user has previously responded with a CONNECT message when the SETUP message has been delivered on a broadcast data link), the network shall stop timer T304 for that user (in the case of overlap receiving); stop timer T303 or T310 (if running); start timer T301 (unless another internal alerting supervision timer function exists, e.g. incorporated in call control); enter the call received state, and send a corresponding ALERTING message to the calling user.
When the SETUP message has been delivered on a broadcast data link, the network shall (at a minimum) associate the call received state with each called user that sends an ALERTING message either as first a response to the broadcast SETUP message or following a CALL PROCEEDING message.