Transport for London has warned Apple Pay users about pitfalls of using the payment service on the UK capital’s travel network.
The transport body says that if your phone dies once you’ve paid, you could get stuck at gates and even face penalty fares.
“Your iPhone or Apple Watch must be switched on to use it to travel,” says TfL. “You should also check that you have enough battery on your iPhone or Apple Watch to complete your journey.”
It continues: “[If] it runs out of battery in the middle of a rail journey, you will not be able to touch out at the end and could be charged a maximum fare.”
The notice adds: “[If] an inspector asks you to touch your iPhone or Apple Watch on their reader, it will not be able to be read and you could be liable for a penalty fare.”
TfL also says that having both an iPhone and an Apple Watch is a potential issue, as a terminal could charge you twice.
Similarly, if you have multiple cards on an account, you need to make sure you use the same one or, again, you could be charged twice.
What’s more, receiving calls while trying to touch in or out of tube gates can cause issues.
But we're still not done. If you’re visiting the UK from abroad and you’re using Apple Pay, TfL says the system may not work, and there’s a risk of being charged currency conversion fees.
Apple Pay went live in the UK two days ago, marking the first time the mobile payment service has been available outside of the US since launch.
If you don’t have an Apple device to use Apple Pay with, check out our iPhone 6 video review below: