Win32 Telephony models a phone's buttons and lamps as button-lamp pairs. A button with no lamp next to it, or a lamp with no button is specified using a dummy indicator for the missing lamp or button. A button with multiple lamps is modeled by using multiple button-lamp pairs.
Information associated with a phone button can be set and retrieved. When a button is pressed, the service provider sends a PHONE_BUTTON message to the tapi32.dll callback function. Parameters of this message are a handle to the phone device and the button/lamp identifier of the button that was pressed. The keypad button '0' through '9', '*', and '#' are assigned fixed button/lamp identifiers 0 through 11.
The function TSPI_phoneSetButtonInfo sets the information associated with a button on a phone device. TSPI_phoneGetButtonInfo returns information associated with a button on a phone device. The service provider sends a PHONE_BUTTON message to the tapi32.dll callback function when a button on the phone is pressed.
The information associated with a button does not carry any semantic meaning as far as TSPI is concerned. It is useful for device-specific applications that interpret this information for a given phone device, or for display to the user, such as in an application's help system.