The libvpb api functions for the programmable tone detector are described here.

General information

When a tone is detected, a VPB_TONEDETECT event is placed on the event queue with the tone identifier in the data element of the event structure. There are 9 pre-defined tones, which default to a selection of standard tones but which may be redefined to suit local requirements. They are:

VPB_DIAL - dial for US
VPB_RINGBACK - ringback for US
VPB_BUSY - busy for US
VPB_GRUNT - grunt detected
VPB_RINGBACK_308 - ringback from Studio 308 PBX
VPB_BUSY_308 - busy from studio 308 PBX
VPB_FAX - fax CNG tone/preamble
VPB_BUSY_AUST - busy/disconnect for Australia
VPB_RINGBACK_AUS - ringback for Australia

Up to 10 tone detectors can be independently defined for each port of each board. To redefine a pre-defined tone, specify its tone identifier as the tone_id parameter of the VPB_DETECT structure when programming.

Programming the tone detectors

The tone detectors may be controlled either by direct calls to the api functions with a user specified TONE_DETECT structure or by setting the VPB_TONE and VPB_TONE1 ... VPB_TONE9 variables in the environment where the application is started.

The parameters required to detect a particular tone may be computed manually with reference to the appropriate standards that define it, or computed from a recorded tone with the assistance of the tonetrain utility which is provided with libvpb.

Todo:: finish fleshing this out, import more (still relevant) details from the sgml docs.