I admit it, credit card processing networks are a complete mystery to me. Having said that, whenever anyone talks about mobile payments the first thing I think about is those little keypads that are standard POS devices now. How exactly would these schemes work? Does the POS device need to be upgraded or is it a network upgrade?

When a customer uses the debit card as a signature card, the transaction is processed over Visa’s network, but if the customer uses a PIN with the same card, it is processed over a separate network.

The signature waiver has reduced transaction processing time, the department said, potentially giving Visa’s signature network an unfair advantage over PIN networks.

[From Visa rescinds debit card rule]