Anatomy of a Credit Card

There are a few topics related to credit and debit cards but many people do not know how much information can be gleaned from the card number. For readers’ information or just entertainment here it is.


This material shows how scammers use public data to help to convince you that they are legitimate.

The current “Visa and Mastercard” phishing scam uses this. They get your phone number somehow, often the phone book for landlines, and call. They ask for you by name and then go on with their script.

At some point they will get around to asking about your card number “you know the one starting with 4 or 5”. People don’t look at card numbers and imagine it is a random number. If you are not thinking this seems almost magical they know the first digit, maybe even that they are being cautious not revealing it all. If you haven’t complained that you don’t have either card then it must one or the other.

All this assumes that you somehow accept that commercial rivals would have the same bureau calling you, that is one bureau would have access to details of both suppliers, which is clearly absurd.

You could conclude that the Visa and Mastercard scam was constructed out of the knowledge that a large proportion of people will have one or the other and the numbers start with 4 or 5.

Why not conduct two scripts, one for each and avoid the absurdity of one call for both? Because the number of hits per call they get rolling the two together even allowing for those who realise it can’t be right is more than making separate calls.


A newer wrinkle. Since the identification schemes are known they can also be and are being hacked.

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