[Freeswitch-users] Fifo: ring agents without answering to caller

Hi everybody. I am using asterisk for a call center pbx and evaluating if I can replace it with FS. With asterisk queue I can ring agents without actually answer to the caller so he won't pay till the agent pickup. Can I do the same with FS ? Moreover I'd really like to fullfill this scenario: I managed to solve it in asterisk only with an ugly workaround. Customer calls the queue and he doesn't get answered for 20 seconds and then he hears welcome message, music and whatever is configured in the fifo. Obviously the agents should ring even in the starting 20 seconds. Any hint or pointer ? Thanks in advance, Massimiliano