Starting in October 2014. 

Currently all iPhone 5s, iPhone 6, iPhone 6 Plus, iPad Air and iPad Mini 3 devices running iOS 8.1.2 and later support Apple Pay. 

Apple Pay is available in the US as a free update to iOS 8. It is anticipated that all future releases of iPhones and iPads will also be enabled with Apple Pay. 

As a merchant, NFC/EMV Apple Pay compatible terminals or the Payline Gateway integrated into a native iOS application and a supported merchant account (Payline Data accounts on TSYS Vital platform).