13.56MHz NFC Phones: Frequency Is Not a Compatibility Promise

13.56MHz identifies NFC's base radio frequency; it does not by itself describe a dual-frequency phone. The NFC Forum technical overview identifies that base frequency and explains multiple NFC protocols and operating modes.

Replace the ambiguous requirement

If a project asks for “dual-frequency NFC,” ask the system provider which two technologies or credentials it means. Record the tag or card type, required protocol, installed app and permitted action. Do not assume one NFC feature covers a second unidentified radio system.

• Confirm the exact phone's documented NFC functions.
• Try an authorized sample tag or credential in the production app.
• Check read location, case interference and the saved result.
• Evaluate each distinct card, service or accessory separately.

Use product facts within their scope

The R4-T product listing confirms NFC support. It does not establish compatibility with every payment, access-control or industrial tag system.

Retain the accepted combination

Use the NFC field-workflow guide to organize the trial. Keep model, software, credential type and observed result together. This article explains the requirement; it does not report a completed interoperability test or certify a service.