This has become an interesting debate, even if straying somewhat from the jokey spirit of Kitz’s opening posts.
Being slightly pedantic I can’t help theorise that, if on-hook suspension did still work, a clever scammer could design his apparatus so as to avoid Burakkucat’s tactics. The scammer could wait s few minutes and then generate his own howler, which he’d stop on receipt of a ‘Suspend’ message (when victim hangs up). Upon ‘Resume’ (when victim goes off hook) he’d generate a fake dial tone, which would be stopped upon receipt of dtmf tones. He’d then start analysing the dtmf digits, recognised sequences being then be met with an emulated response.
To be clear, whilst theorising about the risks, I don’t think I have ever actually, on any occasion, felt personally alarmed by the ‘scammer still on the line’ scenario. But if I were ever worried, would it not be best to simply pick up my mobile and call myself at the suspect line, exchanging a few words to make sure it was really me, after which I’d assume the scammer had scampered?