Petr Kynčl
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All work

A Bluetooth call recorder, at the firmware level

Recents

iPhones can't record calls, especially calls on AirPods. Recents is a small Bluetooth box that sits between the phone and the headset, relays the call in both directions and records both sides, so every call can become a searchable memory.

When
Sep 2026 – now
Role
Founder · R&D
Status
Prototype
  • C
    firmware on an RTOS
  • 2-way
    HFP call relay + recording
  • 0
    changes needed on the iPhone

How it fits together

  1. 1iPhone
  2. 2Recents box (relay + record)
  3. 3AirPods

What I built

  • Firmware that takes over the headset when a call starts, relays both voice streams between the iPhone and the AirPods, records them, and hands the headset back afterwards.
  • A takeover state machine with backoff and collision guards, and reverse-engineered parts of Apple's AirPods control protocol.
  • Python tooling around it: a serial bridge, automated call test rigs, call statistics and Bluetooth capture parsing.

Status

A working prototype, not a product yet. The details of the hardware stay private for now.

Stack

CRTOSBluetooth HFP / eSCOPython test rigs

Next case study

Internát

The end of paper sign-out books in student dorms

Want to talk about it?

[email protected]
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