Try this:
1) Create a queue with your emergency people as members. It's fine if there is only 1 member.
2) Create an in-queue flow that will play your recorded message and disconnect.
3) Use the transfer to ACD action in your normal inbound flow, and make sure to override the default in-queue flow handling to use the in-queue flow you created in step 2.
When your customer calls in and choose the option in step 3, if the queue doesn't have any members logged in & on-queue (), the caller will get transferred to the in-queue flow, hear your recorded message and the system will hang up.
https://help.mypurecloud.com/articles/queue-call-flows/
https://help.mypurecloud.com/articles/set-up-a-transfer-to-acd-action/
https://help.mypurecloud.com/articles/onqueue-offqueue/