A user reports that when calling an auto-attendant, they receive a fast busy signal. Which two options can cause this issue? (Choose two.)

An improperly configured dial peer prevents the CME router from matching or forwarding the inbound call to the auto-attendant application, causing the router to return a fast busy (congestion signal) before the call is ever answered.

If the auto-attendant service is not running, the call would typically connect and then fail during interaction rather than generating a fast busy signal before connection.

If no call-in number is specified on the auto-attendant, the CME router has no DNIS value to associate with that service, so incoming calls cannot be directed to the AA and a fast busy is returned at the routing stage.

A missing prompt allows the call to reach and connect to the auto-attendant but causes silence or an error during playback, not a fast busy signal before the call is answered.

An improperly configured ephone-dn affects IP phone registration and directory number behavior; auto-attendant call routing in Unified CME depends on dial peers and the AA call-in number, not ephone-dn configuration.