Play greeting while listenting for fax tone

I have a user who is complaining about an 8 second “ring” delay when calls come in on his last roll-over fax line(4-port dahdi card to pstn). I have IAX modem setup and fax calls are transfered to this custom extenion if the fax tone has been detected. He claims he has had customers say they didnt think their call went though because of the silence. Any input would be appriciated.