This is one of the easiest ways a phreaker can use to get free phone calls from a public payphone.

It's also the lowest risk category for the phreaker.

When you put money into a payphone, it generates a tone that the operator can hear if she is listening in on the line so she knows when money has been inserted. The duration of the tone depend on the coin value inserted.

The phreaker will call the operator and say the phone won't dial out properly, or he can't get connected. The operator usually offers to connect the call and will ask for the number. Once the operator has dialled the number, she will ask for money to be inserted. The phreaker will then play one of the following tones down the mouthpiece of the phone :-

The tones can be recorded into a dictaphone, or one of the small tapeless recording devices you can buy from Maplin's/Dixons etc. Many phreakers modify tone diallers to enable them to be used for red boxing. As the money starts to run out, the phreaker will play one of the tones down the line again, or will have played them several times when the operator asks for money to be inserted to build up calling credit.