This won’t work. VoIP providers would have to be comprehensively banned.

You can pass the fines the other way. Maybe some VoIP providers decide they do want to be good citizens after all and stop spammers using their service, maybe some decide they like the robocall provisioning business and they'll eat the fines. Adjust the fines until the problem is reduced to acceptable levels.

"Hi, thanks for your enquiry about VoIP. Yes, we have a No Questions Asked policy and it'll be $5000 pcm plus $0.01 per second calls, we need the first $10 000 up front and you need to stay $1000 in credit or we pause service. OK?"

"What! That's crazy, we can't pay 1¢ per second, your competitor is ten times cheaper"

"And my competitor doesn't like spam. Either 1¢ per second is fine or you are wasting my time, get off the line. No questions asked is what you need, and that's what it costs. I paid $25 000 in fines just last week, that's a lot of seconds at one cent per second"

"I'll have you know we're a market leading direct sales business and every one of our calls is based on a legitimate sales lead, but I see your point, the $10 000 will be in your account first thing tomorrow".

They have to provide the IP address of the caller. If it's untrusted it gets blocked. Simple enough. No sympathy here.