Call-Check

Hi, Can someone tell me is it possible to get freeradius respond to Service-Type==Call-Check requests? I have read on cisco's web pages that it is not possible. I am using PM3 RAS with "set call-check on" option set. Namely, I would like to check for valid caller-id before answering the call and going on with username/password check. If it is possible, some pointers would be very appreciated... TIA Ivo.