It's called a termination fee, and it already exists. Alas, it's payable to the receiving operator, not the receiving person - meaning that your telco actually makes money on every single spam call you get. Talk about perverse incentives!
What I'm describing would need to be large enough to be a deterrent, in regards to being truthful or not (or solicited vs unsolicited). That's why I like the idea of something pre-paid but refundable.
There might also be something of value in only refunding the fee to the CNAM entity, which would at least offer some incentive to not lie about being associated.
https://en.wikipedia.org/wiki/Termination_rates