@janbb, as far as the phone company is concerned, it’s just a typical “pay-per-call” number, like any number of “legitimate” (I use the word advisedly) phone sex operations that have been around for decades: “Our girls are just aching to hear from you…” and so forth. The phone company collects the per-minute tolls that are billed to callers, and dutifully remits it to the phone bank operator, no questions asked. That’s a real business model for which the phone company is (or has been) a hands-off middleman. I really don’t “know” this, except for what I’ve read about it from time to time.
They don’t condone or share directly in the operator’s profit; they’re just the common carrier for the “business intercourse”, and this scam is operated the same way: The phone company has nothing to do with the business, but enables it, then collects from callers according to the established tolls, and remits payments to the operator.