User 1 is hosted by VW A and user 2 is hosted by VW B, a mobile phone, or on a chat engine. User 1 has user 2 on his friends list. User 1 looks at his friends list and sees that user 2 is online. User 1 initiates a VOIP voice chat with user 2. The VOIP voice interface is provided by, and integrated into the VW.
I'm in Virtual World B and want to call Totally Virtual, who is not in the World, but is available either on computer via VoIP or via a phone. I want my message to be routed to his current active voice service. (Ability to place and receive calls from voice services in a virtual world and any external phone service)
This is the same case as IM except for voice instead of IM. This depends on Use Case: Presence and Use Case: Friend List.
Standard: routing and service identification; identifying availability (Presence) and routing to selected/available service