TSPI_providerEnumDevices function (tspi.h)

Article
10/05/2021

TAPI calls the TSPI_providerEnumDevices function before TSPI_providerInit to determine the number of line and phone devices supported by the service provider.

Syntax

LONG TSPIAPI TSPI_providerEnumDevices(
  DWORD      dwPermanentProviderID,
  LPDWORD    lpdwNumLines,
  LPDWORD    lpdwNumPhones,
  HPROVIDER  hProvider,
  LINEEVENT  lpfnLineCreateProc,
  PHONEEVENT lpfnPhoneCreateProc
);

Parameters

dwPermanentProviderID

The permanent identifier, unique within the service providers on this system, of the service provider being initialized.

lpdwNumLines

A pointer to a DWORD-sized memory location into which the service provider must write the number of line devices it is configured to support. TAPI initializes the value to 0, so if the service provider fails to write a different value, the value 0 is assumed.

lpdwNumPhones

A pointer to a DWORD-sized memory location into which the service provider must write the number of phone devices it is configured to support. TAPI initializes the value to 0, so if the service provider fails to write a different value, the value 0 is assumed.

hProvider

An opaque DWORD-sized value that uniquely identifies this instance of this service provider during this execution of the Telephony environment.

lpfnLineCreateProc

A pointer to the LINEEVENT callback procedure supplied by TAPI. The service provider uses this function to send LINE_CREATE messages when a new line device needs to be created.

lpfnPhoneCreateProc

A pointer to the PHONEEVENT callback procedure supplied by TAPI. The service provider uses this function to send PHONE_CREATE messages when a new phone device needs to be created.

Return value

Returns zero if the request succeeds or an error number if an error occurs. Possible return values are:

LINEERR_NOMEM, LINEERR_OPERATIONFAILED.

Remarks

In previous versions of TAPI, implementation of this function was optional. Beginning with TAPI 2.0, implementation of this function is mandatory in all service providers. TAPI no longer checks Telephon.ini or the Registry at TAPI startup to determine the initial number of lines and phones supported by a service provider.

A new device can appear prior to the completion of the TSPI_providerInit procedure. TAPI handles properly any _CREATE messages during the provider initialization.

Requirements

Requirement	Value
Target Platform	Windows
Header	tspi.h