Should the calling vendor or the investor own do-not-call compliance

The part that decides it for me is what happens when there's a complaint. If the service owns scrubbing and they've documented every suppression pass, you have something to point at. If you supplied the list, you're the one reconstructing where a phone number came from six months later. I'd rather pay more per contact and have the paper trail sit with the people who built it.

Plumb, the paper trail only helps if you can actually see it. Ask them to show you a suppression report before you sign anything.

The service version of this has an honest constraint built in: scrubbing costs money per record and it never stops costing money. Registries update, litigator lists update, and a list cleaned in January is dirty by March. Any shop quoting a per contact price with scrubbing included has priced that in somewhere, or it is being done once and called done. The question worth asking both shops is how often they re-scrub and what happens to a number after a seller says stop. That answer tells you more about how they operate than the compliance language in the contract does. The split option in the poll is the stronger sell, because the audit keeps the client aware of what they are paying for instead of treating it as invisible overhead.