The scammers are the "last stop" telco carriers. They charge high, Cuban rates to connect someone who thinks they are calling Cuba to a cheap/free recording. They arbitrage the cost of playing a recording (0) against the cost of actually connecting the customer to a party in Cuba (non 0).

These rates are passed up the carrier chain until they reach the caller's main carrier. If international calls are covered in the caller's contract, the carrier picks up the tab. If not, the caller is charged int'l rates for simply listening to a recording.

There should be some way for the main carriers to identify and block these shady "last stop" telcos but it seems as if they have no incentive to as they are probably cheaper to partner with than reputable carriers, and the customer ultimately pays the fee in one form or another.

"My phone call never actually made it to Cuba. The fraudsters make money because the last carrier simply pretends that it connected to Cuba when it actually connected me to the audiobook recording. So it charges Cuban rates to the previous carrier, which charges the preceding carrier, which charges the preceding carrier, and the costs flow upstream to my telecom carrier."

The scammers in this case are apparently a small-time telco. In other cases, the scammers set up 1-900 (or equivalent) numbers and try to get their marks to call the number.