[Freeswitch-users] How can I have FS participate in a shared UDP multicast session/conference?

Hi, I want to have FS participate in a multicast session with other members. I see there is the esf_page_group application available, but I think it will constantly send rtp and therefor will monopolize the port.I think I would need to use VAD my call into esf_page_group.  Is this the right approach?  If so, how can I use VAD? Thanks,David