Acknowledgment messages are sent by the VRU to indicate that a request
has been completed. The Service Control dialog ends when one of the following
conditions occurs:
- The ICM Script controlling the call has run to completion.
- The call ends.
- An unrecoverable error occurs.
The effect of this new method of call handling is that the
ICM, which
has knowledge of the real time call load on a whole network, can instruct
a VRU to perform a specific task, then cancel that request at any point. For
example, this new method can be used to perform VRU queuing where a VRU is
instructed to play music to a caller while the
ICM waits for a suitable
agent to become available. When an agent becomes available, the
ICM can
instruct the VRU to stop playing music and transfer the call to the agent.
In addition to the request or response call control transactions, the VRU
provides event reports that indicate changes in call state. A Service Control
dialog can be defined as a conversation that is between the VRU and the
ICM and
consists of one or more related call-control transactions. A Service Control
dialog provides the context under which the transactions are performed. When
a Service Control dialog has been made, the
ICM controls the VRU call handling
with an
ICM Script. When the
ICM has taken control of a call, the router
keeps call control until the Service Control dialog is ended.