CAS frames are sent and received repeatedly. They consist of 16 frames (octets) on time slot 16. This is a CAS multiframe. This multiframe carries 30 individual CAS signaling channels.
Whenever a CAS frames changes, an event (E1DP_EVT_CAS) is forwarded to the e1d client. The event includes one octet with the CAS information.
The e1d client requests to transmit a new CAS frame by sending a command (E1DP_CMD_CAS). The command includes one octet with the CAS information.
The e1d client requests to receive current CAS frame of a given time slot by setting a query flag in the E1DP_CMD_CAS command. This is useful if the CAS signals changed before the application was started.
The lower 4 bits of each octet in the message represent the signaling sub-channels: A, B, C and D. They are packed like this: 'xxxxABCD'
To enable cas support on an interface, set line attribute "cas" via VTY.
