Surprising that you didn't look hard enough. ;)
ls /usr/local/freeswitch/sounds/en/us/callie/conference/8000/
conf-alone.wav conf-has_left.wav conf-pin.wav
conf-bad-pin.wav conf-is-locked.wav conf-unmuted.wav
conf-enter_conf_number.wav conf-is-unlocked.wav conf-welcome.wav
conf-enter_conf_pin.wav conf-kicked.wav conf-you_are_already_muted.wav
conf-goodbye.wav conf-locked.wav conf-you_are_now_bidirectionally_muted.wav
conf-has_joined.wav conf-muted.wav