Appendix B: ISDN Call Scenarios

This chapter provides charts describing various call control scenarios, including call setup and tear down, network and application initiated call termination, and requests for various ISDN services, using both asynchronous and synchronous mode programming.

The scenarios are presented in the order listed below:

• BRI Channel Initialization and Start Up (User Side)
• BRI Channel Initialization and Start Up (Network Side)
• PRI Channel Initialization and Startup
• Network Initiated Inbound Call (Synchronous Mode)
• Network Initiated Inbound Call (Asynchronous Mode)
• Network Terminated Call (Synchronous Mode)
• Network Terminated Call (Asynchronous Mode)
• Application Initiated Outbound Call (Synchronous Mode)
• Application Initiated Outbound Call (Asynchronous Mode)
• Aborting an Application-Initiated Call
• Application Terminated Call (Synchronous Mode)
• Application Terminated Call (Asynchronous Mode)
• Network Rejects Outgoing Call
• Application Rejects Incoming Call (Synchronous Mode)
• Application Rejects Incoming Call (Asynchronous Mode)
• Glare (Call Collision)
• Simultaneous Disconnect (Any State)
• Network Facility Request - Vari-A-Bill (Asynchronous Mode)
• Network Facility Request - ANI-on-Demand (Incoming Call)
• Network Facility Request - Advice-of-Charge (Inbound & Outbound Calls)
• Application Disconnects Call (Synchronous Mode)
• Network Facility Request - Two B Channel Transfer (TBCT) (Synchronous Mode)
• Non-Call Associated Signaling (NCAS) (synchronous Mode)

Each scenario is presented in tabular format. The tables provide the following information:

• Application - Lists the functions called by the application
• Device Driver - Describes device driver activities including messages sent to firmware and events sent to application (internal activity)
• State - Lists current state (internal activity)
• Firmware - Describes firmware or firmware interface activities and messages sent to device driver and to network interface (internal activity).
• Network - Lists the D channel messages exchanged between the network and the device.

Note: The initials "PI" are used in the tables to indicate Progress Information.

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