[Freeswitch-users] Setting WAV File as rinback

Hi, I'm trying to have an audio as ringback (WAV, 8khz, mono) when originating a call. Unfortunately, it doesn't seem to work; the RINGING teletone is being used instead of my audio. I have debug level enabled on Freeswitch but i don't find anything suspicious. is there anything specific i should be taking into consideration? Thanks, max.