# Using the function reference

This section provides an alphabetical reference to the Voice Message service functions. A typical function includes:

Prototype | The prototype is followed by a list of the function's arguments. Data types include: WORD (16-bit unsigned) DWORD (32-bit unsigned) INT16 (16-bit signed) INT32 (32-bit signed) BYTE (8-bit unsigned) If a function argument is a data structure, the complete data structure is shown.
Return values | The return value for a function is either SUCCESS or an error code. For asynchronous functions, a return value of SUCCESS indicates the function was initiated; subsequent events indicate the status of the operation. Refer to the Alphabetical error summary for a list of errors that the Voice Message service functions return.
Events | If events are listed, the function is asynchronous and is complete when the DONE event is returned. Additional information such as reason codes and return values appears in the value field of the event. If there are no events listed, the function is synchronous.