No, not in Unity (alhtough I'm sure there's switch holding/queuing options external to us that can do this). Unity is extra-sensitive to tying up ports for extended period of time and/or "burning" ports by getting in a state where we loop like that. All our conversation states will eventually back out and terminate the call whenever possible with no user input. You can, of course, go out of your way to configure looping call handlers to do this but even then we'll catch it in the background after X loops with no input and kill the call.
Doing a "hold forever" function isn't on deck for Unity.
Jeff Lindborg
Unity Product Architect/Answer Monkey
Cisco Systems
lindborg@cisco.com
http://www.AnswerMonkey.net (new page for Unity support tools and scripts)