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Appendix D – BRI Supplemental
Services
The ISDN API functions allow BRI boards to perform the following
Supplemental Services:
• Called/Calling Party Identification
• Subaddressing
• Hold/Retrieve
• Call Transfer
• Message Waiting
Call Hold and Retrieve are invoked using the following API functions (see the
appropriate function descriptions in Chapter 5. ISDN Function Reference for
more information):
• cc_HoldAck( )
• cc_HoldCall( )
• cc_HoldRej( )
• cc_RetrieveAck( )
• cc_RetrieveCall( )
• cc_RetrieveRej( )
The other Supplemental Services are invoked by sending information from the
board to the PBX using an appropriate API function. This information is sent as
the part of the Layer 3 frame called the Information Element (see Section
3.2.2. Network Layer (Layer 3) Frames for more information). In order for the
PBX to interpret the Information Elements as Supplemental Service requests, the
Information Elements must be sent as Facility Messages.
The following functions can be used to send Facility Messages:
• cc_SndMsg( ) - Sends a call state associated message to the PBX.