When that one foreign guy is on the pay-phone he calls someone and they give him the toll-free number to an attorney. He calls the attorney, not depositing any money(why would he, it's free) and after he hangs up you can hear coins dropping into the coin-box in the pay-phone.
No one actually answered his question. The question was "why do we hear coins dropping at the end of a toll free call?" I am sure our friend knew what the sound of coins dropping meant. The question is why.