I get these occasional calls and the caller ID says either telemarketer or spam risk. I think one bit of info is the fact that none of those numbers are in my contacts. But how do they distinguish between the two and what info do they use?
They have lists of phone numbers spammers have used. I am on T Mobile and I can flag a call as spam , I assume AT&T , Sprint , and Verizon have lists too.
I’d also imagine that it wouldn’t be too hard to maintain a whitelist of approved telemarketers/nonprofits/etc… and then do traffic analysis to identify phone numbers outside the list that call a LOT of different numbers in a pattern that says “Telemarketer!” As a matter of fact, that’s exactly the kind of thing that machine learning could do very, very well for them, without a lot of manual babysitting.
I suspect that the carriers are watching call patterns, length of calls, etc. to assign phone numbers and blocks of numbers a rating similar to email anti-spam measures. They probably also have honey pot numbers that are used to record calls and then some fuzzy logic against the call’s transcript to look for spamminess.
The battle against telemarketers looks pretty similar to the anti-spam battle. The carriers have (hopefully) learned a lot from email spam over the last 30 years and are now applying similar techniques to phone calls.
What I’m not sure of is why most of the telemarketers I’m seeing are using blocks of numbers that are “local” to my number, but still not very local. Now when I see a call coming from some tiny town with 200 people, it gets hung up on or sent to voice mail.
We have a different system here - I assume that BT have a comprehensive list of undesirables. Most attempts by these callers, in fact, 99% of them, don’t even get through to us.
When the phone rings, caller ID displays the caller as you would expect. If the caller is legit, but not already known, they get a message asking them to say who they are. When we pick up, we get whatever they said and can choose to accept the call as a one-off, accept it permanently or reject it.
So far, we have no complaints - either from legit callers unable to get through, or from us about spam callers getting through.