[Freeswitch-users] Can FreeSwitch be used as a Push-to-talk server?

Hello, I have downloaded freeswitch and read through the wiki document, as far as I know FS can behave as a SIP server which enables both call peers speak and listen at the same time. But I wonder can it act as a push-to-talk server that only one peer speak, the others listen, and use a push button to request for speaking? If I can do this, where to start(may be do some configuration or coding)? My best regards,David