If the line is available (not busy) and the connection is established, the data can be sent. The application accomplishes this by giving control back to the user, who, using a dialog box, specifies the file to send and initiates data transmission. Though TAPI functions continue to manage the opened line and the call in progress, actual transmission is started and controlled by non-TAPI functions. In this case, for example, the Comm API of the Microsoft Platform SDK could be used to control the media stream.
If the application were setting up a speech call, its actions would be similar. Once the call is established, the duty of data transmission is transferred outside of TAPI to the people who want to speak, although the line and call continue to be monitored by the application using TAPI functions.