Two stories about this -

Once in 2014, I got a spam call that spoofed my own number.

This week, I got a spam call that spoofed the number of a family member.

Don't block without being sure.

For the past few years the odd spam call I get has been my number with one digit changed. This came as a surprise when my ex-wife's phone number popped up. I didn't realize it was spam until I listened to the voicemail re: the cruise I won.

How do they go about spoofing the source numbers? That seems like a huge security risk overall for the phone system.

Because there are some good reasons for spoofing Caller ID (e.g. providing a master extension for a call made from a company) and, historically, it was hard/expensive to do. That difficulty pretty much went away with VoIP and other technology changes.

I noticed I end up with a pretty high hit-rate; maybe 1/2 of calls come in already tagged. Maybe I'm just lucky the volume is low enough to answer the calls; if they happened more often it wouldn't be practical.

Some sort of "law" probably comes into play with respect to junk phone calls. If there were a lot more, the phone system would simply become untenable. Instead, between legal, economic, and technology limitations, junk calls (including those that are actually legal) have seemed to hover in the annoying but not a lot worse than that rate for pretty much as long as I can remember.