What is ISO/IEC 15693, and when do you meet it?
ISO/IEC 15693 defines vicinity cards, which work at the same 13.56 MHz as everything else in NFC but are designed for larger antennas and greater reading distance. The NFC Forum adopted it as Type 5. You meet it in libraries, laundries and industrial tracking rather than in consumer stickers.
Proximity against vicinity
The standards vocabulary distinguishes proximity cards, covered by 14443 and intended to be held against a reader, from vicinity cards, covered by 15693 and intended to be readable from further away.
Further away is relative. With a large fixed reader and a card sized tag, tens of centimetres are realistic. With a phone, whose antenna is small, you are back to a tap. The standard permits more range, it does not confer it on hardware that cannot produce the field.
Where it actually turns up
Library books, where a gate reads a tag inside a cover as it passes. Laundry and textile tracking, where tags survive washing. Industrial and medical inventory, where a handheld reader sweeps shelves. Ski passes in some resorts.
What these have in common is a fixed or dedicated reader, not a phone, and a need to read at more than contact distance without moving up to UHF.
What phones do with it
Android exposes it as NfcV and documents it explicitly as ISO 15693 in its technology reference. Apple added support for the family to Core NFC in iOS 13, on the iPhone models that support Core NFC.
Support existing is not the same as support being good. A phone reading a 15693 tag gets a tap, not the distance the standard was designed around, because the limiting factor is the phone antenna rather than the protocol.
Whether to choose it
For anything a member of the public will tap with their own phone, no. Type 2 tags are cheaper, universally supported and behave exactly as people expect. Choosing Type 5 for a consumer deployment buys you compatibility risk and no benefit.
For an internal deployment with dedicated readers where reading at distance genuinely matters, yes, and it is the natural step before jumping to UHF RFID with all the hardware that implies.
The decision is really about who holds the reader. Phones point to Type 2, dedicated hardware opens the question.
Frequently asked questions
Will an ISO 15693 tag read on any phone?
Not reliably. Support is common on recent devices but has never been as universal as for Type 2 tags, and it is one of the areas where older handsets diverge most. Test on the actual population of devices before committing.
Does a vicinity tag read further from a phone?
Barely. The extra range the standard allows depends on the reader producing a stronger field over a larger antenna, and a phone does neither. The gain shows up with dedicated readers, not in your hand.
Is Type 5 the same as ISO 15693?
Type 5 is the NFC Forum tag type built on ISO 15693. The standard defines the radio and command layer, the tag type adds the NDEF layer that makes content readable by any compliant device.
Why do library tags use it rather than Type 2?
Because a book passing through a gate is never held against a reader. The use case needs range at the reader end, which is exactly what the vicinity category was defined for.