I’m guilty of assuming everyone has caller ID these days. While the feature may be baked right into mobile phones, caller ID service for landline phones is still a feature you usually have to pay extra for. And some people don’t want to.

So how should these holdouts handle telephone scams?

My advice is: get on the list and be quick on the draw. First, add your number to the National Do-Not-Call Registry. Once it takes effect, it will weed out all the legitimate, non-scam phone calls. Anyone who calls with an offer or sales pitch after that is obviously ignoring federal regulations and can be assumed to be attempting to commit fraud. If you’ve answered the phone, hang up as soon as you realize what’s happening.

Second, the vast majority of scammers use automated robocalls, where they ring multiple phones at once and then connect with whomever answers first. That setup takes a moment to function, and causes recognizable audio artifacts. If you’ve answered the phone and don’t get a response within a second or so, you can assume it is a robocall and hang up. If you answer and the first thing you hear is electronic noises (little clicks, bloops, beeps, etc.) or silence, it’s safe to assume you’re dealing with a robocall and hang up.

If you’ve hung up on a legitimate caller, they’ll call back.

Failing the quick-draw hang-up technique, if you find yourself talking to an unexpected caller, the old rules still apply: if they’re trying to make you afraid, it’s probably a scam; if the offer sounds too good to be true, it’s probably a scam; never wire money to a stranger; the IRS doesn’t call to demand payment over the phone; you didn’t win the lottery; your grandchild isn’t in jail or a hospital overseas; your computer doesn’t have a virus; never press “1” for any reason.

You’re under no obligation to be polite to someone who is trying to trick you out of your money over the phone. You’re allowed to just hang up without explanation.