Subject: Long distance calls
Telephone cards are by far the cheapest means of phoning long distance, but it now seems they are also the most secure. If one buys a $10 or $20 card, one dials into a long distance carrier different from the one the own telephone provides. The pin code informs this carrier about the length of time the card holder has. If one uses such a card it stops the call once the call has used up the card's value. Usually there is an announcement a few minutes before switch off informing the caller that the card is reaching its limit.

Best regards Joachim