IBM (in Germany) did this at least some years ago. Called the hotline, a nice computer voice told me that all lines are blocked and that they will call me back

IBM (in Germany) did this at least some years ago. Called the hotline, a nice computer voice told me that all lines are blocked and that they will call me back in 12 minutes. After 12 minutes my phone rang and a friendly lady apologised for letting me wait and I told her about my problem. I am still impressed.