If you have a channel abundance, so that you can spare the line. Keep the call connected as long as possible, but route it to a queue, or to a fake auto attendant that just keeps the call live. They will probably see the call connected forever eventually, and remove you from their dialer. If you can conference the inbound call back to itself if toll free, great.
When they see a LD call on the bill for 66,473 minutes, and 32 seconds, I think they will find a way not to call you again. If everyone does this, that gets these calls, they will figure it out, or go out of business paying their LD bill, lol. Also, all their lines will remian busy and they will not be able to call out anymore.