If you just need a message to be played then you could potentially do this via voicemail as well. If you have Unity or Unity Connection, you could configure a call handler (does not require a license) or mailbox for the DN and call forward all to VM. Record the appropriate greeting and set the after greeting action to hang up. When you do this, the call will be forwarded to VM where the greeting is played and then Unity/Unity Connection will immediately disconnect after the greeting.
You won't be able to do this natively with CUCM. IMO, this option is probably the easiest.
Hailey
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