They do usually exist. They answer immediately and than play the "it is ringing"-sound forever.

(Some SIP providers allow you to disallow expensive numbers to be called and/or state the minute costs before the call starts (giving you time to hang up.))

> They answer immediately and than play the "it is ringing"-sound forever.

Except that clearly is a number which exists? One that answers, GP isn't fighting 1980's phreakers with a bluebox, they are using Twilio, Signalwire, etc to make automated verification calls/sms for a very large company as far as I understood it. The call being answered is baked entirely into your programmatic logic.

Unless I'm missing some niche telco semantics or lingo here? Or they are rolling their own?

To embrace the "don't question it, you don't understand" narrative, I'm actually quite stunned someone would let this go on for such a long time, if this is corruption, crime or some other sort of telecom fraud aided and abetted by foreign governments/companies why not just turn off the tap and ban the country code if it was such a cost sink? Why not use some of the many alternative (and significantly more secure) verification methods for your customers?

Countries are demanding access to private citizen encrypted messages,

but can't legislate away the basic 1980s phone scam.

Wonder why their priorities are so skewed.

Corrupt carriers in other countries splitting the money, etc.

So stop dialling out to these few places? Otherwise it's a cost of doing business if you insist on keeping at it knowing full well what happens.

This is what most people do, at my employment we restricted it to US/Canada with a reach out for other countries.