I've just found "System and method for collaborative call management," an interesting SBC Communications patent application for a Graphical User Interface that, according to the patent app, could be used to list the status of participants in VoIP calls.
This patent app (20050149876) was published today on the U.S. Patent and Trademark Office Web site. The documentation was filed by SBC Knowledge Ventures, the intellectual property arm of SBC Communications.
The fact that SBC filed this patent app is evidence that the telecom giant--urrently not a direct player in the IP telephony wars-- is planning enterprise-strength VoIP services and user-configured VoIP software to manage these services.
According to Claim 35, as well several other claims, VoIP calls appear to be the prime application of such an interface.
App says in part:
"A graphical user interface (GUI) element may be presented in connection with a collaborative call. The GUI element may display a listing of call participants and a status of each participant."
As example, participant states could be "on-call state, an off-call state, a currently speaking state, a waiting to speak state, and a paused-call state," the application says. "In operation, information presented in the GUI element may change in response to a status change of a call participant. The method may also involve recognizing that a caller has joined the collaborative call and updating the GUI element to add the joining caller to the list of participants."