True in the UK; https://security.stackexchange.com/questions/100268/does-hanging-up-on-a-uk-landline-call-not-terminate-the-connection https://security.stackexc

True in the UK; https://security.stackexchange.com/questions/100268/does-hanging-up-on-a-uk-landline-call-not-terminate-the-connection https://security.stackexchange.com/questions/100268/does-han... has a decent description of the history and includes a note that BT changed in 2014 from a several-minute timeout to 10 seconds, because of fraud issues. The link to the BT announcement of that change has bitrotted, but it is at https://www.openreach.co.uk/orpg/home/updates/briefings/downloads/wlr00314.pdf https://www.openreach.co.uk/orpg/home/updates/briefings/down...