48 Voice API Programming Guide — June 2005
Call Progress Analysis
7.4.3 Setting Up Call Progress Analysis Parameters in DX_CAP
The call progress analysis parameters structure, DX_CAP, is used by dx_dial(). It contains
parameters to control the operation of call progress analysis features, such as positive voice
detection (PVD) and positive answering machine detection (PAMD). To customize the parameters
for your environment, you must set up the DX_CAP structure before calling a dial function.
To set up the DX_CAP structure for call progress analysis:
1. Execute the dx_clrcap( ) function to clear the DX_CAP and initialize the parameters to 0. The
value 0 indicates that the default value will be used for that particular parameter. dx_dial() can
also be set to run with default call progress analysis parameter values, by specifying a NULL
pointer to the DX_CAP structure.
2. Set a DX_CAP parameter to another value if you do not want to use the default value. The
ca_intflg field (intercept mode flag) of DX_CAP enables and disables the following call
progress analysis components: SIT frequency detection, positive voice detection (PVD), and
positive answering machine detection (PAMD). Use one of the following values for the
ca_intflg field:
•DX_OPTDIS. Disables Special Information Tone (SIT) frequency detection, PAMD, and
PVD. This setting provides call progress without SIT frequency detection.
•DX_OPTNOCON. Enables SIT frequency detection and returns an “intercept”
immediately after detecting a valid frequency. This setting provides call progress with SIT
frequency detection.
•DX_PVDENABLE. Enables PVD and fax tone detection. Provides PVD call analysis
only (no call progress).
•DX_PVDOPTNOCON. Enables PVD, DX_OPTNOCON, and fax tone detection. This
setting provides call progress with SIT frequency detection and PVD call analysis.
•DX_PAMDENABLE. Enables PAMD, PVD, and fax tone detection. This setting provides
PAMD and PVD call analysis only (no call progress).
•DX_PAMDOPTEN. Enables PAMD, PVD, DX_OPTNOCON, and fax tone detection.
This setting provides full call progress and call analysis.
Note: DX_OPTEN and DX_PVDOPTEN are obsolete. Use DX_OPTNOCON and
DX_PVDOPTNOCON instead.
7.4.4 Executing a Dial Function
To use call progress analysis, call dx_dial() with the mode function argument set to DX_CALLP.
Termination of dialing with call progress analysis is indicated differently depending on whether the
function is running asynchronously or synchronously.
If running asynchronously, use Standard Runtime Library (SRL) event management functions to
determine when dialing with call progress analysis is complete (TDX_CALLP termination event).
If running synchronously, wait for the function to return a value greater than 0 to indicate
successful completion.