It is possible to support up to 10, 000 simultaneous users with the correct machine configuration on ConferenceRoom. There is a limitation on the number of simultaneous connections depending upon the end user license. It is automatically set to 10 for the trial version.
/as general set limit 1000
You can choose to set your user limit lower than what your license permits. You might want to do this if you found that your server was having difficulty handling large numbers of clients or if it were a hub and you did not want to overload it. Your server's abilities will depend on the machine it is running on. Experience will probably help you determine what number of clients is right for your server.