2.4.2.7 Generating Inband Digits and Tones

Once in the connected state, information can be transmitted over a call. Two operations are provided that allow end-to-end inband signaling between the TAPI DLL and remote station equipment such as an answering machine. One operation is TSPI_lineGenerateDigits, which signals digits over the voice channel. Digits can be signaled as either rotary/pulse sequences or as DTMF tones. The other operation is TSPI_lineGenerateTone, which enables the TAPI DLL to generate one of a variety of multi-frequency tones over the media stream. This generates telephony tones, such as ringback, beep, busy, as well as arbitrary multi-frequency multi-cadenced tones.

TSPI_lineGenerateDigits

Generates inband digits on a call.

TSPI_lineGenerateTone

Generates a given set of tones inband on a call.

Only one digit or tone generation can be in progress on a call at any one time. When digit or tone generation completes, a LINE_GENERATE message is sent to the TAPI DLL. In the case of generation of multiple digits, only a single message is sent back after all digits have been generated. Calling TSPI_lineGenerateDigits or TSPI_lineGenerateTone while digit or tone generation is in progress aborts the generation currently in progress and sends the LINE_GENERATE message to the TAPI DLL with a cancel indication.