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Doesnt work. Scammers already adopted this to their advantage.

Conman calls a landline, starts conversation with "please call the bank back, im putting down the phone now" and ... just plays Dial tone. The trick is call ends only when the person who started it hangs up.

Hmm... "No worries, I'll do that but it'll probably be in a few days as I'm pretty busy now."

If they want to leave their line open "for a few days"... then good luck to them. :)

A good one. Or if it’s something you really should verify right away, call your friend or relative first. If the scammer answers again, you’ll definately know.

Good tactic, that'd work. :)

Except its your 60 year old mum answering the call, and 'calling back' just made her absolutely sure she can trust the nice bank lady on the phone.

or call a friend before calling the number

This was an issue with UK BT POTS lines some years ago. The line would 'hang' for a fair while after the recipient hung up before clearing down (disconnecting both sides).

The idea was, maybe you dropped your phone and didn't mean to hang up and this gave you time to rectify your mistake without having to redial.

Scammers started exploiting this and the timeout was reduced to the order of a few seconds. Count to five after hanging up and you can just about guarantee that's a real dialtone.

If you hang up and pick back up too quickly, yeah. But the call doesn't just stay connected until the cake hangs up. Either party can end it by hanging up, right?

Landline calls, at least when I was younger, were not disconnected until the caller hung up. I assume there’s a technical reason involving channels instead of packets but I never researched it.

Landline calls were disconnected after a timeout. The receiver could hangup and pick up quickly and still be connected. We used this method to move to another phone in the house. Also if you tapped the hook a few times the line would disconnect

Technical reason was mechanical exchanges (Strowger etc) https://www.youtube.com/watch?v=xUOh9fCSgqw

implementing logic/timers with cogs is impractical.

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