How to identify paid phone numbers?

Question

Telephony

Hello. We want to protect users from scammers who indicate paid phone numbers in ads. How can this be organized?
Is it possible to get a list of paid numbers from the operator? Or an API through which you can check the number?
On the Internet I found only templates (8-809*, 8-801, 8-802*, 8-803*) that are paid.

Answer 1

By law, the operator is required to give a voice warning to the subscriber before a paid call.

Answer 2

And what other numbers besides those indicated in the header can be paid?
There are expensive long-distance and international calls. But that's not exactly what the question is about.