lineHold function (tapi.h)
The lineHold function places the specified call on hold.
LONG lineHold( HCALL hCall );
Handle to the call to be placed on hold. The application must be an owner of the call. The call state of hCall must be connected.
Returns a positive request identifier if the function is completed asynchronously or a negative error number if an error occurs. The dwParam2 parameter of the corresponding LINE_REPLY message is zero if the function succeeds or it is a negative error number if an error occurs. Possible return values are:
LINEERR_INVALCALLHANDLE, LINEERR_OPERATIONUNAVAIL, LINEERR_INVALCALLSTATE, LINEERR_OPERATIONFAILED, LINEERR_NOMEM, LINEERR_RESOURCEUNAVAIL, LINEERR_NOTOWNER, LINEERR_UNINITIALIZED.
The call on hold is temporarily disconnected allowing the application to use the line device for making or answering other calls. The lineHold function performs a so-called "hard hold" of the specified call (as opposed to a "consultation call"). A call on hard hold typically cannot be transferred or included in a conference call, but a consultation call can. Consultation calls are initiated using lineSetupTransfer, lineSetupConference, or linePrepareAddToConference.
After a call has been successfully placed on hold, the call state typically transitions to onHold. A held call is retrieved by lineUnhold. While a call is on hold, the application can receive LINE_CALLSTATE messages about state changes of the held call. For example, if the held party hangs up, the call state can transition to disconnected.
In a bridged situation, a lineHold operation may possibly not actually place the call on hold, because the status of other stations on the call can govern (for example, attempting to "hold" a call when other stations are participating is not be possible); instead, the call can simply be changed to the LINECONNECTEDMODE_INACTIVE mode if it remains connected at other stations.