Worth mentioning of course, that calling the bank to check whether a call is a scam needs to be undertaken carefully. It's not unheard of for scammers to simply pretend to hang up, whereas actually they keep keep the line open, maybe even playing a fake dial tone. Instead of calling the bank, the victim is just resuming the conversation with the scammer.
Not sure of current protocols but in the days I was vaguely involved in related technology, the line would be disconnected as soon as the calling party hung up, but was merely suspended, staying connected for a timeout (a further 2 minutes I think) if only the called party hung up. This was a feature useful where there were several hard-wired extensions. It allowed a subscriber who had picked up an incoming call on an inconvenient extension to hang up the first handset, then make their leisurely way to another room, and pick up the call again on another handset.
