Advanced guides
Advanced Signal guide: safety numbers, PIN and Registration Lock
Understand safety numbers, PIN and message requests for more confident private conversations.
Reviewed: 2026-09-22 · Refer to the current app and official guidance
Compare conversation safety numbers
Safety numbers verify the encryption of one-to-one conversations, not a person’s real-world identity.
- Open the conversation, go to chat settings and select View Safety Number.
- Prefer scanning the other person’s QR code in person, or compare digits through a channel you already trust.
- Once the numbers match, select Mark as Verified.
Changing phones or reinstalling may change the safety number. If the change is unexpected, confirm with the contact before continuing a sensitive conversation.
Understand and manage your Signal PIN
Your PIN helps restore your profile, settings and contacts. Chat history needs a separate backup or transfer.
Mobile: Signal Settings → Account → Change PIN
- Choose a numeric or alphanumeric PIN you can store safely.
- Distinguish your PIN, SMS code, device passcode and backup recovery key.
Signal cannot recover or reset your PIN. A PIN cannot restore lost chat history.
What Registration Lock does
Registration Lock adds PIN verification when re-registering. Before enabling it, make sure your PIN is safely stored.
Mobile: Signal Settings → Account → Registration Lock
- Open account settings on your registered, working phone.
- Follow the current app’s instructions to enable or disable Registration Lock.
If you forget your PIN after enabling it, you may need to wait up to 7 days. See the official instructions for the recovery process.
Choose which message requests to accept
Message requests let you see who is contacting you before deciding whether to continue.
- Review the profile and visible shared groups in a message request.
- Choose to accept, delete or block. Accepting shares your Signal profile with the sender.
- Phone-number visibility and discovery can be adjusted separately in privacy settings.
More about Signal
From understanding to everyday use.
Read the help guides or choose the version for your device.