zlacker

About 15 years ago I was using telephone banking, when you had to put in a 4-digit PIN to access banking. I could still hear background call centre noise so I asked the operator if they were still on the phone when I put the PIN in, and he confirmed he was.

"Okay, so you heard me type in the PIN? So now you can know my PIN?"

"Oh no", he said, "it's just beeps, like this - ", and pressed a few digits.

"Right so you typed 1 6 3 2 4, there."

"..."

"That's what you typed, isn't it?"

"Uhm... yes, how did you guess?"

"I didn't guess, I could hear the beeps. I've got a reasonable ear for pitch, so I can tell what the numbers are from the tones. Any chance you could escalate this to your manager after the call, and tell them to give me a phone if they've any questions?"

They rang me the next day, and I explained the situation to them.

Now, at least in the UK, you get transferred away from the call handler when you put your PIN in.