I think the easiest is yes, you have a Call Forward No Answer CFNA pointing to a pilot number on Unity Connection.

In Unity connection you create a call handler that will accept the call on that pilot number and play a recording or something you have created.

Hope it helps or points you in the correct frame of mind or direction.

CUCM usually doesn't play media. There are some exceptions around the Annunciator service but it's not configurable and doesn't have CFNA in it's repertoire. The only options I can think of OTHER than Unity are:

1. Contact Center Express / IP IVR
2. A TCL script on the ingress PSTN gateway

Please remember to rate helpful responses and identify helpful or correct answers.