So let me start this with just stating that this is for educational purposes only, and by no means would I expect this to be appropriate in a production environment.
Would it be possible to set a timeout limit in UCM for redialing a specific number?
Case study - User calls support desk and gets voicemail, and the instructions in the voicemail state to leave a voicemail and support team will call them back, or they can press "2" to leave an urgent voicemail. Instead of leaving a voicemail, the end-user continues to redial often times redialing the number 7 or 8 times within 90-120 seconds.
Wait the end goal would be is to limit that users ability to redial, or have their calls go straight to voicemail until "X" amount of time has passed.