Maybe the Route Congestion Message (from Settings menu) could be used to send the call to a Queue with a fixed route or something? I certainly haven’t tried it.
Trunks so expensive where you are that it would make sense to pay employees to wait rather than to buy enough truck space to carry the traffic? Either your labor cost are super low, or your phone cost is super high. I can’t get my head around when it would make sense to do this.