how do scam calls generate random phone numbers?


I’ll get a call and sometimes no one even answers me when I pick up and then I will call it back and get the “this # has been disconnected ” response. How does that work?

In: 14

It’s called phone number spoofing. You can make your calls appear like they are coming from a different number.

It’s also possible that they are coming from valid numbers that are not set up to receive incoming calls.

If some one is calling from a system equipped with trunks, there will be a number assigned to outbound calls, and another range for in bound calls. The number is most likely assigned as an outgoing only number.

The telephone systems allows you to set your caller id to anything you like, it’s not set for you based on your number.

This lets you do things like show up as a your business name, but often gets abused to display an incorrect callback number so you don’t know whos calling and can’t call them back.

Why this system is so open and abusable I have no idea….

Ok. Alongside spoofing (making your number appear like a different one) covered by a few other people in this thread, different telephone companies are allocated blocks of telephone numbers in each country or city.
Some of these telephone companies will then allocate ‘smaller’ blocks of these, called DDI ranges, to other companies – who could be unscrupulous shell companies linked to scam call companies in India for example.
That way, using something called SIP trunks (voice over Internet Protocol via Session Initiation Protocol) they can use the internet as the backhaul, and then breaking out in the local telco hiding behind these DDI’s, they make calls appear like they are coming from your town or city – in the same way you used to be able to buy local telephone numbers in any country from Skype – so having a custom number in the USA when you live in the U.K. for example, except these scammers do it in bulk.

They then start calling people via what looks like a local number (can even be a mobile number although the U.K. mobile telco’s seem to have started to crack down on that) but it’s enough to fool people into thinking it could be a friend etc.

When that number is ‘dirty’ and starts appearing in spam block lists, they just move on to the next in the range and so-on.

(This is enormously simplistic as there is technology underneath to provide the SIP trunks & you’d need something to connect to the local Telco. As an ex employee of a couple of telco’s I can attest to it being a whack-a-mole where people report one of your numbers to be a scammer and by the time you’ve shut it and all the ranges down for shell company X, then you find shell company Y is already using a new range with a new telco & so-on.)