1. client make a phona call to 30000 to trigger a dialplan.
2. The dialplan should launch a script to allocate an available conference room for me and return a customized to the client,maybe there is a variable just like conf_room:3001 in return sip message body. I know I can simply dial 3000 to join a default conference,but I am writing an client,if user A and B and C is using the 3000 conference,at this time,user D,E,F want to have a conference,then they will get 3001.