[MichaelZuo]

The scammer in a foreign country has to have on-the-record account(s) with some foreign telecom company, directly or via some chain of intermediaries.

Just shut down those accounts, and if the foreign telecom doesn't comply, then block calls incoming from that telecom. Eventually the scammers will start encountering serious resistance to obtaining new accounts and numbers.

So why hasn't anyone done this yet?

[icedchai]

They don't necessarily need to use a foreign telecom company. They can buy SIP access directly from a US company (Twilio, SignalWire, etc) and use it anywhere.

[MichaelZuo]

Then that's even easier, because a US company's customer accounts are under the authority of US courts.

[icedchai]

You would think so. However, the number of scam/spam calls I receive daily proves otherwise. When I look up these numbers, they are mostly CLEC or mobile numbers. I assume some of the caller IDs are still spoofed, though I thought STIR/SHAKEN was going to fix that.

Approximately 50% of the calls I receive are through a company identified as "Sinch". Some complaints about them here: https://scammer.info/t/sinch-and-inteliquent/85531

Sadly, scams are big business.

[MichaelZuo]

The reported names can be entirely spoofed, but the telecom engineers know who they are connected to, and the companies they are connected to know who they are connected to ad infinum.

[icedchai]

What's the incentive to do anything about it?

[MichaelZuo]

Money?