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Signal supports up to five devices on a single account: your primary phone and up to four additional linked devices. Linking lets you use Signal on a tablet, desktop, or a second phone with the same phone number and identity.
Linking requires an active internet connection on both devices.

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How linking works

When you link a new device, your Android phone acts as the primary (device ID 1). The secondary device generates a QR code; your phone scans it and completes the cryptographic handshake. Signal then issues the new device its own set of session keys so it can send and receive messages independently. Optionally, your phone can upload an encrypted message archive during linking (Link and Sync) so the new device starts with your existing message history rather than an empty inbox.
1

Open Signal on the device you want to link

Install Signal on your tablet or computer. On the Signal desktop app or Signal on a second Android device, choose the option to Link existing account or Link to Android rather than registering a new account.The secondary device will display a QR code.
2

Open Linked Devices on your primary phone

On your primary Android phone, go to Signal Settings (tap your profile icon) → Linked Devices.If you have not linked any devices before, you may see a short introduction sheet. Dismiss it to continue.
3

Tap the link icon and scan the QR code

Tap the + button or the QR scan icon. Signal opens the camera.Point your phone’s camera at the QR code displayed on the device you want to link.
If your camera is struggling to read the code, tap the front/rear camera toggle to switch lenses.
4

Confirm linking (with or without sync)

Signal shows a confirmation prompt. If the secondary device supports Link and Sync (it advertises the backup5 capability in the QR code), you will see the option to sync your existing message history to the new device.
  • Link and sync — Signal uploads an ephemeral encrypted backup from your phone and transfers it to the new device. This gives the new device your message history.
  • Link only — The new device joins your account but starts with an empty message history. It will receive new messages from this point forward.
Tap Link to confirm.
5

Wait for the process to complete

Signal connects to the new device and completes the key exchange. If you chose to sync, Signal generates and uploads an encrypted archive. Progress is shown on screen.Once linking is complete, you will see a toast confirming the device name (e.g. “Signal Desktop linked”).
Sync can take up to 60 seconds to confirm the device connection. If it times out, Signal will notify you and you can retry.

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What syncs to linked devices

After linking, Signal keeps your devices in sync in real time: Linked devices use your account’s ACI identity key pair and PNI identity key pair so they can participate in the same end-to-end encrypted sessions as your primary device.

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Manage linked devices

After linking, you can see and manage your secondary devices from Settings → Linked Devices. The list shows each device’s name, when it was linked (createdMillis), and when it last connected (lastSeenMillis). Signal polls for device updates every 5 seconds for 60 seconds after you open the Linked Devices screen to keep the list current.

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Rename a linked device

Tap a device in the list to edit its name. Signal encrypts the new name with your ACI identity key before sending it to the server, so the server never sees plaintext device names. Tap a device and select Unlink. Signal immediately revokes the device’s access — it will no longer be able to send or receive messages on your account.
Unlinking is immediate and cannot be undone. The unlinked device will stop receiving messages. To use Signal on that device again, you must go through the full linking process.
If Signal detects that a device you just linked has already been unlinked (for example, you cancelled the sync), it will show a dialog to let you know the device was not successfully added.

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Security considerations

Physical access

Anyone with physical access to a linked device can read your Signal messages on that device. Lock your devices with a PIN or biometric authentication.

Device limit

Signal enforces a limit on the number of linked devices per account. If you hit the limit (status code 411), you must unlink an existing device before adding another.

QR code validity

The QR code generated by the secondary device contains an ephemeral identifier (uuid) and public key (pub_key) for a one-time handshake. It is valid for a short window — if the link attempt times out, the secondary device will generate a fresh code.

Sync archive security

When using Link and Sync, Signal generates a random 32-byte ephemeral key for the archive. The archive is uploaded to Signal’s CDN, and only the new device receives the decryption key. The archive is not reused after the link completes.

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Reviewing your linked devices

Periodically review your linked devices list to confirm you recognize every device. If you see an unfamiliar device, unlink it immediately and consider re-registering to rotate your cryptographic keys. Signal also runs a background job (LinkedDeviceInactiveCheckJob) to detect devices that have been inactive for an extended period and clean them up.

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Troubleshooting

The QR scan does not register Make sure both devices are connected to the internet. Try toggling the camera (front/rear) if the scanner is having trouble reading the code. The secondary device may need to regenerate the QR code if it has expired. Sync timed out If Link and Sync does not complete within 60 seconds, Signal will show a timeout dialog. You can choose to link without sync (the new device joins but without message history) or cancel and retry the full flow. Not enough storage If your phone does not have enough free space to create the sync archive, Signal will report a storage error. Free up space and try again, or link without syncing. Device shows as already unlinked If Signal shows a dialog saying a newly linked device was immediately unlinked, the secondary device likely timed out waiting for the link to complete on its end. Restart the linking process from the beginning.