That's pretty much the proposal I've made for some years.[1]

California has introduced bonding to telemarketing firms specifically. I feel that should apply at the carrier level, where networks carry a guaranteed bond, pay regular premiums on it, and are dinged for unwanted calls, with the proceeds being split among the called party and any third-party network(s) traversed by the calls. Downstream networks could seek compensation from ANY upstream network carrying the traffic regardless of whether or not they originated it.

This would both create a penalty for providing, or transiting, unsolicited calls, AND create an incentive for carriers / network providers themselves to pursue unsolicited traffic from their peers.

<https://oag.ca.gov/consumers/general/telreg>

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Notes:

1. See for example <https://toot.cat/@dredmorbius/111099306069523624>