DRAWING NO. TLR-2026 SHEET 4 / 4 MODE PRIMARY OR LINKED DETOUR ONLY NEXT TO OFFICIAL SIGNAL STATUS TESTED ANDROID + iOS
◄  YOUR ACCOUNT, ONE OR TWO APPS  ►POS. D-01

Setup Signal für GNU as your Signal app, or linked next to the official one

[4] Signal für GNU is a full Signal client. It can be your primary device: register your phone number in it, as in the official app, and no detour is needed. Only if you want to keep the official Signal app does Signal für GNU join your account as a linked device, like Signal Desktop. All tests ran this way. The only tricky part there: when both apps are on the same phone, that phone has to scan its own screen. A second camera solves it.

← Sheet 1: Pitch ← Sheet 3: Install Choose your way Primary device Linked, same phone Linked, different phones After setup
D-02 Choose your way
A · PRIMARY DEVICE

Signal für GNU is your only Signal app

  1. You register your phone number in Signal für GNU.
  2. No official Signal app needed, no QR code, no second camera.
  3. Steps: D-03.
B · LINKED DEVICE

You keep the official Signal app

  1. The official app stays the primary device, Signal für GNU is linked to it.
  2. Both apps show the same chats, nothing is registered again.
  3. Same phone: D-05, with the detour over a second screen. Different phones: D-06.
D-03 A · Signal für GNU as the primary device
STEP BY STEP
  1. Install Signal für GNU and GNU Taler für Signal (Sheet 3).
  2. Open Signal für GNU and tap Create account.
  3. Enter your phone number and the verification code, then set your PIN and profile, as in the official app.
  4. Continue with D-07.
MIND

A phone number has only one primary device. If your number is already registered in the official Signal app, registering it in Signal für GNU moves the account away from the official app. If you want to keep the official app, take way B and use Link your account instead.

D-04 B · Linked device: before you start
YOU NEED
  1. The official Signal app with your account (the primary device).
  2. Signal für GNU and GNU Taler für Signal installed (Sheet 3).
  3. If both Signal apps are on the same phone: a second device with a camera and a screen, e.g. another phone or a tablet.
DO NOT

On this way, do not tap Create account in Signal für GNU and do not register your phone number there. That would make Signal für GNU the primary device and move your account away from the official Signal app. Always use Link your account.

D-05 B · Both apps on the same phone
THE TRICK — THE CODE TAKES A DETOUR OVER A SECOND SCREEN
PHONE A Signal für GNU
  • shows the QR code
take a photo
→
PHONE B Second camera
  • shows the photo on its screen
scan the photo
←
PHONE A Official Signal
  • scans it under "Link new device"
STEP BY STEP
STEP 1 ►

Phone A: open Signal für GNU

Link your account
  • On the welcome screen tap Link your account.
  • The app shows "Scan this code to link your account". Tap Maximize QR Code.
STEP 2 ►

Phone B: take a photo of the code

sharp, straight, no glare
  • Fill the frame with the code and check that it is sharp.
  • Open the photo on phone B and turn its screen brightness up.
STEP 3 ►

Phone A: switch to the official Signal app

use the app switcher, do not close Signal für GNU
  • Tap your profile picture to open the settings.
  • Tap Linked devices and Link new device, confirm it's you.
  • Point the camera at the photo on phone B.
STEP 4 ►

Phone A: back to Signal für GNU

"Linking device…"
  • Signal für GNU finishes the link and loads your contacts and groups.
  • The official app may offer to transfer your message history; both choices work.
DONE ►

Both apps on one account

official Signal stays primary
  • Signal für GNU appears in the official app under Linked devices.
IF IT DOES NOT WORK
  1. Be quick: the code belongs to a live connection of Signal für GNU. If it shows a new code, "Failed to generate code" or an error, tap Retry and take a new photo.
  2. Instead of a photo, a screenshot of the code works as well, sent to any other device with a screen (laptop, tablet).
  3. The camera does not focus: hold phone A a bit further away from the photo, avoid reflections, increase the brightness of phone B.
D-06 B · Official Signal on another phone
NO DETOUR NEEDED

If Signal für GNU runs on a different phone than your official Signal app, scan directly: in Signal für GNU tap Link your account; in the official app tap your profile picture, Linked devices, Link new device, and scan the code on the other phone. On both test phones, the iPhone 12 mini and the Fairphone 6, Signal für GNU ran as a linked device.

On the iPhone the procedure is the same with the TestFlight build of Signal für GNU.

D-07 After setup
1 · TEST MONEY

Open GNU Taler für Signal and withdraw KUDOS from the demo bank at bank.demo.taler.net. No real money is involved.

2 · FIRST PAYMENT

Open a chat in Signal für GNU, tap + and Send with Taler (iOS: Taler Payment). Enter the amount and confirm in the wallet, as on Sheet 1.

3 · REMOVE AGAIN

Linked (way B): in the official Signal app open Linked devices, tap Signal für GNU, Unlink. Then uninstall the two test apps. The official Signal app and your account are not affected.

Primary (way A): to move back, register your number in the official Signal app again, then uninstall the two test apps.

The menus are named as in the English version of the apps; on a phone set to another language they appear translated.

TITLETALER IN THE CHAT — SETTING UP SIGNAL FÜR GNU
DRAWNA. LENKENHOFF
CHECKED—
DATE2026-11-10
DRAWING NO.TLR-2026
REVISION1.1
SHEET4 / 4