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Periphery

How to identify an unknown Bluetooth device on iPhone

Look at what the device advertises and what services it exposes, that is the whole trick. Scan with Periphery, tap the device, and read the card at the top of the inspector; it names common types, Heart Rate Monitor, Nordic UART Device, whatever matches its services. Past that, the service names plus a quick Read of its information fields tell you most of what is left.

3 min read · Updated 2026-10-06

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Why an unknown device shows up on Bluetooth

BLE devices just never stop advertising. A neighbour's fitness band, a smart light, a keyboard, someone's tracker, a sensor through the wall, any of it can land in your scan. Plenty carry no name at all, so they sit there as Unknown plus a code. Most are harmless. Still, it helps to know what is actually talking to you.

How to identify an unknown Bluetooth device with Periphery

  1. Tap Scan and set Sort by to Strongest signal. A device that stays near the top as you move around the room is probably close to you.
  2. Tap the device. Periphery connects and shows Connecting… while it discovers the device's services. If the device refuses within 10 seconds, you see an error instead.
  3. Read the card at the top of the inspector. It shows a device type and a percentage match, with one line explaining what that type usually is.
  4. Scroll through the services. Known ones are shown by name, such as Device Information, Battery Service or Heart Rate, with the raw UUID underneath.
  5. If there is a Device Information service, tap Read on Manufacturer Name, Model Number or Firmware Revision and switch Format to ASCII to read the text.
  6. To find where the device physically is, go back, swipe its row and tap Locate.

What the device card can recognise

All the card does is compare the device's services against a short built-in list. There is no product database behind it, just families recognised by what services they carry.

Types the device card can name
Service it looks forCard shows
Heart Rate (180D)Heart Rate Monitor
Nordic UART (6E400001-...)Nordic UART Device
FFF0Xiaomi Device
Human Interface Device (1812)HID Device
Environmental Sensing (181A)Environmental Sensor
Cycling Speed and Cadence (1816)Cycling Computer
Cycling Power (1818)Power Meter
Blood Pressure (1810)Blood Pressure Monitor
A specific ESP32 example service UUIDESP32 Device
Shelly BLU service UUIDShelly Device
None of these, but standard short UUIDsStandard BLE Device
None of these, only long custom UUIDsCustom BLE Device

How to read the percentage match

It is just the share of services that matched a known type. 3 services with one Nordic UART among them shows 33%. 5 services with one Heart Rate shows 20%. Matched nothing at all, and it still shows 30%, which trips people up every time. A low number is not a wrong guess; most devices carry general services that identify nothing on their own.

When the card says Custom BLE Device

Custom just means it uses its own UUIDs, nothing else. You can still learn plenty: the advertised name, whether Battery Service or Device Information is present, what its characteristics return when read, how the signal shifts as you move. A strong signal that holds steady in every room of the house usually means it is near you, not through the wall at the neighbour's.

An unknown device connected to your iPhone is a different question

Periphery only lists what is advertising nearby. It has no view into what your iPhone itself is paired or connected to; that list lives in the iPhone's own Bluetooth settings, not here. Connected devices often stop advertising the moment they pair, so they can vanish from any scanner's list entirely.

Questions and answers

Why does a device show as Unknown?
It simply advertises without a name; sensors, trackers and accessories do this a lot to save space in the radio packet. Periphery shows Unknown plus the start of whatever identifier iOS gave it.
Can Periphery tell me the brand of any device?
Not as a rule. It only recognises a short list of device types from their services. Beyond that, reading the Manufacturer Name characteristic, if the device bothers to offer one, is the most direct way to see who made it.
Why does the same unknown device appear twice?
Privacy rotation, mostly. A lot of devices swap their private Bluetooth address from time to time, and iOS then treats the new address as a brand-new device, same hardware, different row.

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