Breakdown: How does contactless work?

18 March


With contactless becoming an everyday action that your cards, including your Allstar Plus card, can do, we thought it was a good idea to look at how they actually work.

What is it?

Contactless is the newest payment method in your credit, debit (or Allstar Plus) card, but it’s also found in car keys, smartphones or tablets.

How does it work?

Inside a contactless card there is a loop of copper around the edges of the card (an antenna) which houses your account information. This picks up power from a signal sent from the card reader when it’s between 2 - 10cm away. 

The card reader will then emit an electromagnetic field that turns the card ‘on’, allowing the reader and the card to communicate with each other using an encrypted language. This means the reader can ‘introduce’ itself to the card with the data amount. In return, the card will ‘reply’ with a coded data transfer, which the reader will then confirm, usually instantaneously.

Why do we need it?

For ease and convenience. The most you can spend at a time is £30, but there is no limit how many transactions you can make in a day (unless, with your fuel card, you have specific limits set). It allows you to pay for your transactions easily, meaning you don’t need to remember specific PINs or passwords to be able to buy items.

Anything else?

There have been some instances of having a card clash when using public transport, like the Underground. It happens when you place your wallet on an Oyster terminal that deducts the payment from a card you did not intend to use. Then when you dock out with your Oyster (or another) card, you’ll be charged two maximum fares as you haven’t touched in and out with the same payment method.

While we have not tested the effectiveness of doing so, some people use metal cases or line their wallet in foil to prevent it from being read without you wanting it to be.

Want to know more?

Call your contactless provider to know more about specific cards, but for more about contactless cards, you can find out more here: contactless cards or contactless consumer.

To find out more about the Allstar Plus card, you can look here: Allstar Plus

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