Unsuccessful outgoing call (common channel signaling)

This section describes the sequence of events when Blueworx Voice Response makes an outgoing call on behalf of an application, using a common channel signaling process.

Figure 1. Common channel signaling process: unsuccessful outgoing call
The graphic is a very simplified representation of the process described in detail in the next section. The graphic shows the phases that are explained there.

Error processing

Blueworx Voice Response provides error processing to ensure that a call is never left connected in the event of failure. This table shows what Blueworx Voice Response does when a channel process failure occurs at different phases during the establishment of an outgoing call:

Phase

Error Processing

A

None.

B

Send the SL_CALL_ABORT_REQ primitive to the signaling process.

Due to channel negotiation, the pack and channel may not be determined until after the call is established. In this case, the pack and channel on the SL_CALL_ABORT_REQ may be set to SL_UNDEFINED_VPACK and SL_UNDEFINED_CHAN.

Z

None.

Description of flows

  1. A: The application state table issues a MakeCall action. This action is processed by the application channel process, which is part of Blueworx Voice Response.
  2. The channel process creases an SL_CALL_SETUP_REQ primitive.
  3. B: The channel process sends the SL_CALL_SETUP_REQ primitive to the signaling process.
  4. The signaling process receives the request primitive from the signaling interface.
  5. The signaling process establishes the call to the network using whatever protocol it supports. The Initial Address Message is used to establish the call. In this case the call establishment is unsuccessful. The Release message from the network indicates that the call was not connected, the cause indicator parameter gives the reason why the call failed.
  6. The signaling process completes the SL_CALL_SETUP_CNF primitive. The ReplyCode field must be set to a value other than SL_REPLY_SUCCESS. See SL_CALL_SETUP_CNF primitive for a description of how the values of the SL_REPLY_CODE enumeration are interpreted by Blueworx Voice Response. Use the ISDN_UP cause indicator parameter (or its equivalent for other signaling protocols) to select the most appropriate ReplyCode.
  7. Z: The signaling process sends the SL_CALL_SETUP_CNF to Blueworx Voice Response.
  8. The channel process has been waiting for a reply to its request.
  9. The channel process maps the ReplyCode to result, which it returns to the state table.
  10. The MakeCall action completes, and the state table continues with the next action.
Parent topic: Example signaling flows