The tapi/phone device class consists of all phone devices. You access these devices using the TAPI phone functions.
DWORD dwDeviceId; // phone device identifier
The dwDeviceId member is the identifier of the phone device associated with the phone handle given by phoneGetID.
DWORD adwDeviceIds; // array of phone device identifiers
The adwDeviceIds member is an array containing the device identifiers of all phone devices that are associated with the given line device. If there are no associated phone devices, lineGetID returns the LINEERR_INVALDEVICECLASS value.