Here are the steps to verify that your smartphone is ready for NFC reading:

1. Ensure that NFC on your smartphone is enabled. On most smartphones, you can check by making sure the NFC icon is turned on in the menu that appears when swiping down from the top (on Android) or swiping up from the bottom (on iOS). In all smartphones, there is usually a specific option in the Settings section. Note: On the latest versions of iOS/iPhone, NFC is enabled by default.
2. Perform the reading with the phone unlocked and the screen active. This step is very important because most smartphones do not activate the NFC reader when the screen is off or on the lock screen/pin request screen.
3. Slowly move the smartphone over the device until you find the position of the NFC antenna. Try both on the back of the smartphone and on the screen. On Android devices, it is usually located on the back, either at the top or in the center. On some versions of the iPhone, it is located at the top, and reading is easier when performed on the front (screen side).