Inside Macintosh: Telephony /

Chapter 4 - Call Appearances / Call Appearance Reference

Call Appearance Functions / Calling Back an Unavailable Party

TELCallbackSet

Requests either a notification or a return call when a destination number that is currently unavailable (busy or unanswered) becomes available.

pascal TELErr TELCallbackSet (TELCAHandle hTELCA, short *callbackRef);

hTELCA

A handle to the call appearance structure for the currently unavailable destination number.

callbackRef

A pointer to an identifier for this callback request. You provide the pointer. The function returns the identifier.

function result

A result code.

DESCRIPTION

You call the TELCallbackSet function to make a callback request. If the function executes successfully, your call appearance message handler gets a telCACallbackMsg message with the value parameter set to telCallbackEst. What happens subsequently depends on whether the destination was originally busy or did not answer.

If the remote number was busy, then when it is no longer busy, your call appearance message handler gets a telCACallbackMsg message with the value parameter set to telCallbackNowAvail. You can respond by calling the TELCallbackNow function (page 4-43) to ring the number again. (Some switch vendors refer to the Callback feature as the Ring Again feature.)

If the remote party did not answer, the return call must be initiated by the remote party (because there is no way to detect locally when the remote party is available). If the remote party is running an application that uses the Telephone Manager, the remote application's call appearance message handler gets a telCACallbackMsg message with the value parameter set to telCallbackDesired. The remote end can then return the call by calling the TELCallbackNow function.

SEE ALSO

You use the TELCallbackNow function (page 4-43) to call back a previously busy number or to respond to a remote party's callback request.

You can cancel a callback request by calling the TELCallbackClear function (page 4-44).