Build the hardware

The phone is a compact 3D-printed base with an off-the-shelf analog G-style handset that plugs into a 3.5 mm jack (for example the Opis 60s Micro). All electronics sit on one small, deliberately minimal circuit board (2 layers, 53 parts): an ESP32-S3 module, one USB-C port for power and flashing, one 3.3 V regulator, twelve hot-swap mechanical keys and a hook switch, a socket for a ready-made 2.13” e-paper display module, an audio codec for the handset, a piezo ringer and one status light. There is no battery, NFC, speaker, per-key lights or hardware mute switch.

The board has no microphone of its own. The only microphone is the one in the handset: unplug the handset and there is no microphone connected at all; while the handset is hung up the software keeps its mic muted (see the security model). The phone is mains/USB-powered like a landline: no battery by design, it is not a mobile device. Hardware is licensed under CERN-OHL-S-2.0.

Status

Hardware v0.1 is an early dev board prototype (silkscreen rev A, 156 × 88 mm, 2 layers, 53 parts): four phones on the first boards, made by JLCPCB, are built and working, running the experimental labs build (0.0.0), lightly tested so far. Expect a revision: we recommend trying a virtual phone first and waiting for board v1.0 before building your own. The exact manufacturing files (Gerbers, BOM/CPL, schematic and layer PDFs, STEP) and the build and flash guide are in the hw-v0.1 release.

Board v0.3: coming soon

For tinkerers: board v0.3 will be offered fully assembled or as a bare PCB to populate yourself. No price or date yet. Join the interest list and say which you’d want.

Read in this order:

1. Hardware overview — what’s in the hardware/ folder.
2. Hardware design — parts, board, pin map, power budget, cost.
3. Design guidelines — safety and layout rules every board follows.
4. Schematic — how the schematic-as-code is built and checked.
5. Layout checklist and Assembly — what the 2-layer layout must meet, and building the board (JLCPCB first; any PCB house or hand assembly).

Your keys, your server

A phone you build depends on nobody, this project included:

• No server until you choose one. Its setup page asks for your Wi-Fi and a server: My own server (its address) or Public hub (free, to try it). Change it later with MENU → 4.
• No updates unless you set them up. Firmware built from source has no update key and checks nothing. To update your own phones, make your own key (firmware/tools/release.sh keygen) and publish to your own channel. Only the project’s official firmware downloads take the project’s updates.
• Its device key is made on the phone and never leaves it. If you turn on Secure Boot, it uses your key.

Details: “Your keys, your server” in the firmware reference.

Until the boards arrive

Until then, the browser phone behaves like the hardware phone: same keys, same screens. The phone firmware (0.9.x: Wi-Fi setup from your phone, pairing, calls with two-way audio, voicemail, Lounge phones, updates) builds with ESP-IDF and runs in a simulator; see the firmware reference and its changelog. When a board arrives, Bring-up is the checklist for trying it.

Then make it do more

The same board runs the labs firmware: a house intercom, a doorbell, a daily check-in, a Home Assistant panel, a macro pad and a few games. See also make it yours and versions and releases.