Launched a year ago, several of America's biggest banks already incorporate Zelle within their apps, while a recently introduced standalone app lets anyone access the service through the debit card accounts.

And customers are flocking to the network, with an average of 65,000 signups a day during the third quarter, resulting in 60 million payments worth $17.5 billion.

The network now claims more than 50 financial institutions and can expect to grow thanks to a new collaboration with IBM which will see any bank using Big Blue's Financial Transaction Manager get access to Zelle and the capability to send and receive customers' money in seconds.

According to IBM, the deal give banks the first solution to support the full lifecycle of P2P transactions, from the back office to the mobile device - without heavy IT spend or disruption to legacy systems.

"The integration of FTM with Zelle not only accelerates and simplifies payments through real-time processing between banks and consumers, it enables same-day deposits and bill pay, removes fees, and offers seamless cash flow, all while remaining compliant with regulatory requirements," says Alistair Rennie, GM, Watson Financial Services Products, IBM.

He adds: "For customers, this means being able to securely send and receive money in minutes, rather than waiting 1-2 days to 'cash out' which is standard among other providers such as Apple Pay and Venmo. This solution removes the friction typically experienced with other providers who essentially serve as a 'digital check' and not real time payments."