enter callers to queue and remove and ring when available?

Is it possible to enter callers into a Queue (say example 200) and then when an agent is available have it ring and leave the queue? So, it wouldn't enter the queue if there are agents available.

I have tried routing all calls through the ring group and fail over to a queue. But if I have a call on the extension (100 example) then it would be disconnected if someone enters the ring group or queue .
I have set the queue to fail over to 200?
I really dont know what to do now?

RE: enter callers to queue and remove and ring when available?

The definition of the Queue is to keep callers in line towards a number of agents, when they become available. As far as I know queues function properly in this respect on PBXes.

If the Queue is empty and there is no "Join Announcement", the caller will proceed to the first available agent without any delay.

What kind of functionality are you looking for, that a Ring Group needs to be involved?