Cisco Cisco Computer Telephony Integration Option 9.0 Developer's Guide

optional_args

An optional input parameter, which is a pointer or reference to an Arguments 
array that contains a member with the string value that is the UniqueObjectID 
of the call to which this call should be conferenced. If this argument is used, 
it should be added to the Arguments parameter with the keyword of 
“CallReferenceObjectID”. This would only be necessary in an environment 
where there are multiple held calls and the request is being made through the 
talking call. If the request is being made through a specific held call in this 
scenario, or if there are only two calls at the device, this parameter is 
unnecessary. 

errorcode

An output parameter (return parameter in VB) that contains an error code 
from 

 in 

Default CTI OS return values. See 

Before making this request, it is necessary for the original call to be in the held 
state and the consult call to be in the talking state or the request will fail. 
Therefore, if the calls are alternated (see Alternate), they must be alternated again 
to return the two calls to their appropriate states.

If there are only two calls at the device, this method may be called using either the 
current or held call. For switches which allow more than two calls at a device (for 
example G3), make this request through the desired held call to avoid the 
ambiguity caused by multiple held calls at the device. Otherwise, indicate the 
desired held call using the optional parameter.

The Conference request must be made via a call whose call status is 
LCS_CONNECT or  LCS_HELD or it will fail.

On certain switches (notably IPCC), only the Conference Controller (the party 
that first initiated the conference call) may add additional parties to an existing 
conference call.