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London Transport (uk.transport.london) Discussion of all forms of transport in London. |
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card numbers, was cards, was E-ZPass, was CharlieCards v.v. Oyster(and Octopus?)
On 02-Mar-12 08:39, John Levine wrote:
Dunno why yours would have a 6 number other than that buying a range of numbers from whoever runs 6xxx was cheaper than from Master card or Visa. One of the reasons for the 3/4/5/6 distinction is that, before the advent of modern card processors, a merchant would have to decode the card number to figure out which network to call for authorization and submit the charge to. They could only process card types they knew and from networks they had an existing relationship with. 4/5 cards were easy to deal with because only the first number needed to be examined, which is why Visa and Mastercard are so widely accepted. 3 cards are only slightly more difficult. 6 cards, though, were generally only accepted at the particular merchant that issued them. An ATM machine might have only understood the particular 6 ranges used by a handful of ATM networks. My HSBC UK debit card used to have a 6 number (which worked in card terminals in the US, I tried it) Today, things are totally different. Merchants send all transactions to the same card processor, regardless of card number, and it's up to the processor to route it to the right network and issuing bank. It's then up to the issuing bank to decide whether to accept a charge from the merchant in question. Sears card, for instance, started accepting charges from any merchant, rather than just Sears stores, and rebranded themselves Discover. Ditto for many other 6 issuers. However, many 6 issuers still only accept charges from particular merchants for various commercial reasons. but they have since switched to Visa numbers, likely so that they're usable at places in the US that only do signature transactions. 6 numbers work just fine in the US for signature transactions; Discover has worked that way for a long time. Until you've bought $20 worth of tickets, it works normally, and the ticket price is deducted from your balance when the transaction clears. After that, the bank rejects the transaction, but if the guard's ticket machine doesn't validate in real time, by the time that happens you're long gone, and since the card is a bearer instrument, they have no way to know who to go after. Repeat indefinitely until the expiration date on the card. Knowing the BIN ranges of debit cards and gift cards doesn't help here, since many of them are entirely valid and the train company will get paid. Exactly my point. S -- Stephen Sprunk "God does not play dice." --Albert Einstein CCIE #3723 "God is an inveterate gambler, and He throws the K5SSS dice at every possible opportunity." --Stephen Hawking |
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