You can only accept a swipe transaction with Stripe Terminal readers if a card doesn't have a chip or as a fallback if chip reading fails. When a card is swiped, a three-digit code embedded in its magnetic stripe indicates to the reader whether the card has a chip or not. If the card does have a chip, readers are required to reject the swipe and prompt the customer to insert the card.

Internet-connected sPOS Terminal card readers that support magstripe will notify the customer visually that they should insert their card if they try swiping the card first and the card has a chip. If reading the chip in the card fails, the reader automatically displays a screen instructing the user to either try inserting the card again – or if necessary, to swipe it through the magstripe reader. If the customer swipes their card when instructed, the reader will authorise the card with the magstripe data.

Bluetooth and USB-connected mPOS Terminal readers, such as the Stripe Reader M2 and the BBPOS Wisepad3, function similarly. If the customer swipes a card with a chip, the mPOS reader will not accept the swipe. If the mPOS reader fails to read a card chip, it will allow the customer to authorise the card with magstripe data. Your app should display the input methods allowed (e.g. "Swipe, Insert" ) and other reader display messages (e.g. "Retry Card") to the user. For more information, see Handling reader display events.