[radford-neal]

Really? You'd press the button when your friends call?

Or, if you phoned a store to ask whether they stocked an item you want to buy, do you think the store would press the button?

At any rate, people already (often) pay to make phone calls. By dealing a number, you're implicitly agreeing to pay. Just think of it as a charge (often waived) for the time of the person answering it.

[mostlystatic]

People could submit their phone number anywhere that collects leads (be it dentists, charities, or SaaS companies), wait for a call, and then press the button to get the money.

[radford-neal]

Maybe. And how much money do you think you'd loose each year due to such scams? Maybe 50 cents?