That is really great. I've had a lot of trouble with calls from spoofed numbers a couple of years ago (it ended when I installed a scam blacker on my phone), and when I looked into it at that time, my impression was that phone companies couldn't block spoofed numbers. On the other hand, if the scam blocking app can block them, there clearly must be some way to detect them.
Phone companies need to do a better job protecting their customers against this abuse.
The fact that the phone companies haven't done this or much else yet goes to show how little they care.
E.g. in Finland the relevant regulation (https://traficom.fi/files/media/regulation/M_28_L_EN.pdf) says (in section 10):
> Telecommunications operators must block calls terminating from the public international interface when the calling party number is clearly incorrect or the calling party number is a Finnish telephone number and the situation does not involve roaming as referred to in section 7.2.1.
This is good but not far enough. They should not show up as "private number" they should simply now show up at all. After some time, any networks that even allow spoofed outgoing calls should be disconnected from the phone system.