What are the CAP1.1 API commands in CAPI.DLL?

The Common-ISDN API (CAPI) specification requires that all complient CAPI 1.1 drivers provide the following functions to any application that wishes to use them.

API_INSTALLED This command checks whether the CAPI 1.1 system is installed and operational on the machine. If CAPI is not installed an application should not attempt to use any CAPI services.
API_REGISTER This command registers an application with the CAPI system and initialises any internal structures. After this command an application can begin to use CAPI services such as dialling and listening for calls.
API_RELEASE This command releases an application from the CAPI system and frees any internal structures allocated with the API_REGISTER command.
API_PUT_MESSAGE This command allows an application send a CAPI message to the CAPI system. The CAPI messages allow an application perform all the standard ISDN functions with an ISDN card.
API_GET_MESSAGE When the CAPI system wants to send a message to the application it places it in an internal queue. An application should call this command to check for any pending messages.
API_SET_SIGNAL When a CAPI message becomes available from the CAPI system, a callback function can be called to notify the application. This command is used to specify what callback function (if any) should be used
API_GET_MANUFACTURER This command is used to determine the manufacturer of the CAPI system.
API_GET_VERSION This command is used to determine the precise version of CAPI 1.1 supported by the CAPI system.
API_GET_SERIAL_NUMBER This command is used to determine the serial number (if available) of the ISDN card.
API_GET_ADDRESSMODE This command is used to determine the type of memory that the CAPI system requires for its internal buffers. This memory is either DOS memory (below 1MB) or standard Windows memory.