I've got an IP Telephony installation with CCM 6 and a H323 gateway for ISDN calls. The receptionist phone has a DID extension. When someone calls it from the outside after two rings if the receptionist does not take the call, it's automatically disconnected and the person who's calling gets the busy tone. I tried to fix this by adjusting the ring duration of the phone (under line configuration) but I still get the some problem. What could be the solution for that.