NFC might not be top of the list for Apple, but it's the iPhone that's being used by Visa in association with the RBS and Nat West for the TouchPay service.But interestingly, not the most recent iPhone. The phone you'll need for the service is the iPhone 4 or iPhone 4S. Even then, you'll have to get in the queue, as the service, when offered initially for trial, was oversubscribed. So just 1,000 of the 9,000 who pre-subscribed will be invited in. Don't worry, if it's successful, TouchPay is likely to roll out universally. We suspect that will happen sooner rather than later.If you are one of the lucky 'few', just attach the associated iCarte Visa cover to your iPhone and follow the on-screen instructions to download the TouchPay app from the Apple App Store. Once the activation process is complete, you can use your smartphone for transactions of £20 or less at mobile contactless-enabled retail outlets without entering a PIN, and track your spending through the TouchPay application.Ben Green, Head of Mobile at RBS, commented: 'TouchPay has proven incredibly popular and shows that our customers want more flexible and convenient ways to pay. Delivered alongside our updated mobile apps, the TouchPay service means that our customers need only carry their smartphone with them to make payments and manage their finances wherever they are.'If you are not in the trial, but would like to get in that queue, full details are on the NatWest site.