New Orleans Cash, coins and credit cards are so Twentieth Century.

At least, that's the opinion of the electronics manufacturers, phone companies, banks and credit card issuers that expect mobile phones to be the main way consumers pay for purchases in the not-so-distant future.

The trouble is, that vis-ion-of-tomorrow is somewhat blurry, as evidenced at the US mobile phone industry trade show held last week in New Orleans. There are a lot of ideas, but little agreement.

The stakes, however, are high.

"Eighty-five per cent of the world's transactions are still made with cash and cheques. We have a wonderful opportunity to convert those," said Gary Flood, MasterCard's president of global products and solutions, in a keynote speech at the show.

One concept that gets a lot of attention is the "digital wallet" — a virtual repository for our credit card numbers, receipts, coupons. It's not much different from a PayPal account, which can be linked to different cards.

A lot of companies see the wallet as the key to influence in the world of mobile payments, especially if it sits on a mobile phone, not just on a PC. Google introduced its Wallet last year. It's available on a few phones that can be tapped against certain payment terminals to complete a payment.

Andrew Lorentz, a lawyer at Davis Wright Tremaine LLP who works with the payments industry, said at the show that if he had a dime for every digital wallet that's been announced, he'd be rich.

"I can have more wallets than cards," he said.

At the show, MasterCard announced a service that could speed up wallet proliferation even more. The company's idea is to let any company that wants to set up its own wallet.

"The idea behind this is: How do we get more wallets and more innovation?" said Ed Olebe, MasterCard's senior vice president of e-commerce development.

Consumers trust their banks, he said, and might want to keep their cards in a bank-branded wallet. Banks, meanwhile, want to extend their relationships with customers, tying them closer. Stores may also want their own wallets, taking the step up from issuing loyalty and credit cards.

MasterCard's wallet, revealed at the show, will be live this autumn and ready for purchase on Barnes & Noble's website and through the American Airlines phone app. Instead of entering credit card numbers, users on those sites will be able to tap a button, jump to their wallets, pick a card and check out.

Valuable information

A crucial question is what information the wallet issuer will be able to see about a consumer's transactions. There's valuable information there that could be used to target marketing offers or for loyalty programmes. MasterCard is still working out those details, Olebe said.

"There's a myriad of laws and rules we have to apply," he said. "We don't want to push the envelope on that."

There's no guarantee that MasterCard's wallets will work on phones for tap-to-pay transactions at the register, either.