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Voice API for Windows Operating Systems Library Reference — November 2003 471
3
3.Events
This chapter provides information on events that may be returned by the voice software. The
following topics are discussed:
• Overview of Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471
• Termination Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471
• Unsolicited Events. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473
• Call Status Transition (CST) Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473
3.1 Overview of Events
An event indicates that a specific activity has occurred on a channel. The voice host library reports
channel activity to the application program in the form of events, which allows the program to
identify and respond to a specific occurrence on a channel. Events provide feedback on the
progress and completion of functions and indicate the occurrence of other channel activities. Voice
library events are defined in the dxxxlib.h header file.
Events in the voice library can be categorized as follows:
• termination events, which are produced when a function running in asynchronous mode
terminates
• unsolicited events, which are not generated in response to the completion of a function. Rather,
they are either generated in response to a condition of a given function or as a result of a call
status transition (CST) condition that has been met.
• call status transition (CST) events, which indicate changes in the status of a call, such as rings
or a tone detected, or the line going on-hook or off-hook. CST events are unsolicited events
that are produced as a consequence of setting a CST mask.
For information on event handling, see the Voice API Programming Guide. For details on event
management and event handling, see the Standard Runtime Library API Programming Guide.
3.2 Termination Events
Termination events are produced when a function running in asynchronous mode terminates. To
collect termination event codes, use Standard Runtime Library (SRL) functions such as
sr_waitevt( ) and sr_enbhdlr( ) depending on the programming model in use. For more
information, see the Standard Runtime Library documentation.