This sounds like a creative way of scamming a pay-per-call advertiser. But, I can't imagine any of the 'big boys' in the pay-per-call market risking something like this.
The 'big boys' might avoid it by policy, but perhaps a rogue affiliate/commissioned-salesperson benefits.
Or, it could be competitors doing a denial-of-service attack on inbound calls, or a marketing-budget-depletion-attack on a pay-per-call campaign.
One way to deduce more: were the numbers he called the most commonly-advertised numbers for the target businesses, or other numbers through some tracked dispatch?
Can't tell if the numbers were the most commonly advertised ones, but he does note that "Aaron" told him this:
"...all you are doing is calling a company that we provide the number for, pressing the correct (1) or (2) – which we specify..."
If I'm interpreting that right, they're using inside information to get him up the phone tree to the right person (whatever their definition of "right" is).