Assume everyone asking for such things are scammers.
That's excellent advice, and everyone should follow it. Unfortunately some banks disagree and will cancel your credit cards when you fail one of their fraud check phone calls.
> And guess what, the only way to be sure that it’s your bank you’re talking to, is to call them yourself. Period. Some callers tell you details of your account as a way of identifying themselves.
There's a scam in the UK where they call you, and ask you to call them back. You hang up, then pick up the phone and dial the number. But because they initiated the first call the line doesn't clear until they hang-up, and they don't hang up while you're dialling the number. (And the sometimes play recorded ring tones before they "answer").
That sounds more like a hoax of a scam. I doubt the phone system works that way.
> When do you stop paying for a phone call?
> Call charging ends when the telecoms company disconnects the call. This is usually but not always when the caller hangs up and the call appears to end.
> Voice calls The caller originating the call must hang up for the call to end. The person receiving the call may hang up, but this will not end the call unless the originating caller also hangs up. Only when the originating caller hangs up then will call charging end. You should always check you've replaced the receiver correctly. If you have any concerns that your call has not ended, you should check that you have a dial tone - this indicates the previous call has ended.
Here's a story from the shitty Register about this method of scamming people:
I don't think I've ever heard of anyone being harassed in this way. A few pranks, maybe.
The behavior certainly isn't replicated on mobile phones.
See also: London Underground.