It's not chip and signature it's chip and pin, it's not good enough to just have the card for purchases you need to know the 4 digit pin and enter it into the terminal at the time of purchase. No pin no purchase, we don't accept UK cards without it and will do a Code 10 on foreign cards without it over a certain amount. NFC cards which is what I assume you mean by blink, normally incorporate chip and pin can only be used for smaller amounts (~£10-£15) paying by NFC as you don't need to enter anything to verify your identity. Larger amounts need to be done via chip and pin so that the identity of the purchaser can be verified.