On 26-Feb-12 13:04, Roland Perry wrote:
In message , at 12:51:52 on Sun, 26 Feb
2012, Stephen Sprunk remarked:
There are still two steps: the merchant gets authorization at the time
of purchase and then posts the transaction at some later time,
potentially several days later.

You may not be _aware_ of the second step, but it's there.

It's a plausible theory, but I don't understand why it would be like
that with C&P. The card company is sent all the details in order to
provide authorisation. Why would they need to be sent it again?

I'm not sure. There might be a good legal or financial reason for the
separation, but it might just be a historical artifact left over from
the days of imprints and telephone authorization.

Does an ATM have this "two pass" process as well?

The major ATM card networks (eg. Plus and Cirrus) are owned by the major
payment card networks (eg. Visa and Mastercard), so I doubt they work
_too_ differently.

Also, at least in the US, ATM cards have been mostly supplanted by debit
cards. Some "ATM" cards are really debit cards with a $0 "purchase"
limit. Some banks still issue real ATM cards on request, but many
can't/won't.

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