Vox Baby: Who "Owns" My Telephone, Anyway?: "Second, hanging up immediately is the non-cooperative response to this problem. When the Samwick household receives unsolicited phone calls (and I'm talking about you, Car Store), we employ either of two strategies that have a common element. If the VoxSon is feeling punchy, we let him answer the phone and have a little fun. Otherwise, we answer the phone, possibly responding that we will 'go get' the person in question, and then just put the phone down.
The common element here is that we keep the offender on the line as long as possible. This prevents the offender from bothering the next household on the call list until the offender terminates the call. This is the way to tax the resources (i.e. time) of the offender, making the enterprise less profitable and thus less likely in the future. If we all cooperated to employ this strategy, we would all be better off for it.
So the next time your phone doesn't ring during dinner, you can be grateful to me, since I'm probably keeping that telemarketer on the line. But whatever you do, don't call to thank me."
Oil, Oil, Toil and Trouble (Update 4)
21 minutes ago