Tagattitude's TagPay uses sound waves to securely transmit payment information without the need for the near-field communication chip that many mobile wallet systems are being designed around.

The French company's sound-based system, which it calls NFC2.0, also generates dynamic data that is unique to each transaction – if this data is overheard or stolen, it cannot be reused.

"The audio signal is actually a one-time password coded into inaudible frequencies of sound," says Isabelle Berner, head of marketing for Tagattitude. "By sending a unique signal to one device and having that signal picked up by another device, this allows the NFC2.0 server to 'pair' the two devices with an extremely high level of security."

A merchant's smartphone must be enrolled in the NFC2.0 platform to establish a link with its bank. The merchant initiates a transaction using the application by typing the payment amount onto the phone or tablet and sending it to the acquiring bank. The app responds with a sequence of audio frequencies played through the merchant's phone.

The customer then hits "pay" on his or her mobile app, prompting the phone to pick up the nearby signal. The preauthorization is sent to the issuing bank's server, where the transaction is either approved directly or pending a requested PIN code, Berner says.

Because Tagattitude does not sell software directly to consumers (it develops payment programs for banks and others in the payments industry), it is up to banks to promote its NFC2.0 system, she says.

"Overall, TagPay-based services have been embraced favorably up to now, and we expect that with the addition of our new NFC2.0 technology, usage and uptake will grow much more quickly for those with smartphones," Berner says.

NFC2.0 solves a problem on the consumer end by allowing many more phones to use the application, but securing merchant acceptance may be difficult, Zil Bareisis, an analyst with Celent, says.

"Merchants need to be part of this scheme, which we've always maintained is incredibly hard for anyone to achieve," Bareisis says. "While I am optimistic about PayPal's capabilities to extend their merchant relationships, I think it will be very hard to do the same for most others."

It will take time for Tagattitude or any other provider to develop a standard for mobile-payment systems, Gareth Lodge, another analyst with Celent, says.

"As I like to say, debit cards are the overnight success that took 20 years to happen," he says.