1. Negative Acknowledgement - When the switching function supports service requests that perform connection creation process and the switching function detects a failure, the negative acknowledgement can be used to indicate the failure to complete the connection. The following are the service requests associated with connection creation process:
If the switching function uses the negative acknowledgement to indicate the connection failure, then the appropriate error code will be used to indicate the particular failure.
- Consultation Call
- Deflect Call
- Dial Digits
- Join Call
- Make Call
- Make Predictive Call
- Pickup Call
- Single Step Conference Call
- Single Step Transfer Call
2. Support of the Failed Event with an Associated Failed Connection - When the switching function detects a connection failure, it places that connection into the failed state. This indicates that the call control services which can be performed with respect to the connection are limited. The following is the list of call control services that are applicable:
When a connection enters the Failed state, the event sequence provided is a Failed event. The characteristics associated with this event sequence are:
- Clear Call
- Clear Connection
- Call Back Call-Related
- Call Back Message Call-Related
- Camp On Call
- Deflect Call
- Intrude Call
3. Support of the Failed Event without an Associated Failed Connection - This case is similar to the �Support of the Failed Event with an Associated Failed Connection� state (case 2). The difference is that when the switching function detects a connection failure, it does not create a connection for the failed device but instead indicates to the computing function that call control services, with respect to the connection, are limited. The following is the list of call control services that are applicable to the connection in the call under these conditions:
- The Failed event will have an appropriate failure event cause.
- The failedConnection parameter in the Failed event will contain a �complete� Connection Identifier (i.e., a Connection Identifier that has both a Device Identifier and Call Identifier)
- The Failed event will be reported to all active device-type monitors associated with the call, as well as all call monitors associated with the call.
When the failure is detected, the event sequence provided is a Failed event. The characteristics associated with this event sequence are:
- Clear Call
- Clear Connection
- Call Back Call-Related
- Call Back Message Call-Related
- Camp On Call
- Deflect Call
- Intrude Call
If the Camp On Call or Intrude Call service request is performed, then the connection associated with the failed device will be created (i.e., a valid connection).
- The Failed event will have an appropriate failure event cause.
- The failedConnection parameter in the Failed event will contain a �Call ID only� Connection Identifier. This indicates that there is not a valid connection for the failed device in the call but that the appropriate call control service can be performed (i.e., Call Back Call-Related, Intrude Call, etc.). In the figures for the services and events, this �Call ID only� connection identifier is indicated via a dotted line (see Clause 11 for the template descriptions).
- The Failed event will only be reported to the active device and call monitors associated with the devices that where in the call prior to the failure (i.e., if a device-type monitor was on the failed device, then the event sequence is not reported).
4. Support of the Failed Event with an Associated Failed Connection, not reported via monitors on the failing device - This case is similar to the �Support of the Failed Event with an Associated Failed Connection� state (case 2). The difference is for which monitors the Failed event is being sent: The Failed event will only be reported to the active device and call monitors associated with the devices that were in the call prior to the failure (i.e. if a device-type monitor was on the failed device, then the event sequence is not reported). Apart from this, all aspects from case 2 apply also to this case.