ANZ and Visa are conducting a one-month trial where mobile phones can be used as credit cards when waved in front of a payment reader.

The trial will be carried out with 50 people who will have a built-in memory card inserted into their Apple iPhone case. The device can be used for purchases up to $100 with no signature needed.

Mobile phone manufacturers are yet to build the new technology into smartphones, however Visa Australia country manager said the trial was intended to prove consumers wouldn’t have to wait.

"We are still waiting for handsets to become available and this is a way to bridge that gap and use the technology today," Mr Kalra said.

"It's been a real eye-opener so far and it's interesting to see the reaction of people around it. They say 'how can I get one of these phones?'"

DeviceFidelity partnered with Visa to build the special cases. The cases have a MicroSD memory card that uses an app and a prepaid debit card to complete transactions. Mobile phone manufacturers could soon be building new phones with the cards already inserted inside. The new technology could be available in the US as early as this year, with Australia following closely behind.

Experts warn security could be a concern with the technology, especially as some people lose mobile phones more than credit cards.

The smartphones compatible with In2Pay microSD technology include the Samsung Galaxy-S i9000, Blackberry Bold 9650, iPhone 3GS and the iPhone 4.