Most recently, Google made me jump through some hoops: they decided that in GMail, an SPF* record status of “neutral” is now enough for them to consider incoming messages as spam. So Google wants to make sure that the email server they’re receiving a message from is actually authorized by the domain owner to send this message. That’s what SPF does. I didn’t have an SPF record set in my DNS configuration, so I added one, and everything’s fine again. The SPF system works.
We need a similar technology for phone calls, to prevent numbers from being spoofed. If you ever received a text message like “Who’s this” or received a voice message “Hello, I’m just returning your call” (from a number you didn’t call, text, or even know), then your own number has been spoofed too, and used to place spam phone calls to someone.
I received a lengthy voice message once, from a rather angry, elderly man, who said that he had “nothing to with debts”, and of course that I should “stop calling!” – at the time I found it mildly amusing, but the number of “neighborhood scam” calls (where the first six digits of the calling number is the same as yours) has increased a lot since then. And then the scammers/spammers of course use my phone number to place their outgoing calls, too.
Apparently, no one is interested in hunting them and shutting them down?
Without knowing the inner workings of placing phone calls, I really wonder how hard it could be to prevent this. After all, my number is connected to ONE single SIM card, which is in one single device (my mobile phone), which has a unique IMEI number. No one else should be able to place a call with this number if these parameters aren’t met.