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By default, Signal accounts are tied to a phone number. Signal provides two complementary tools to limit how much your number is exposed: discoverability controls (who can look you up by number) and usernames (an alias you can share instead of your number).

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Who can find you by phone number

Signal’s contact discovery tells other users whether a phone number belongs to a Signal account. You can restrict this to prevent new people from finding your account via your number. To change this setting:
  1. Go to Settings → Privacy → Phone number.
  2. Under Who can find me by number, select Everyone or Nobody.
Changing discoverability to Nobody does not remove you from the contact lists of people who already have you as a Signal contact. It only affects whether your account shows up when someone checks a number they do not already have a conversation with you from.

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Creating a Signal username

A username is an identifier like alice.42 that you can share in place of your phone number. Anyone who knows your username can start a conversation with you on Signal without knowing your phone number, and without your phone number appearing in the conversation. Usernames follow the format nickname.discriminator, where the discriminator is a numeric suffix (for example, alice.42). The discriminator distinguishes accounts with the same nickname and cannot be chosen freely.

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Set up your username

1

Open your profile

Tap your profile icon at the top of the conversation list to open your profile settings.
2

Tap Username

Tap the Username field, or go to Settings → Account → Username.
3

Choose a nickname

Enter your desired nickname. Signal will show available discriminator options. Select one and tap Save.
Usernames must be at least 3 characters and can contain letters and numbers. Usernames are not case-sensitive.

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Sharing your username

Once you have a username, you can share it in several ways:

Share link

Signal generates a signal.me link tied to your username. Share this link anywhere — social media, email, a website bio — and anyone who taps it can start a conversation with you in Signal.

QR code

Signal generates a QR code that encodes your username link. Others can scan it with the Signal camera to open a conversation immediately.
To find your username link and QR code:
  1. Go to Settings → Account → Username.
  2. Tap Share username to see the QR code and copy your signal.me link.
Your signal.me link uses a cryptographic username link that does not directly embed your username in the URL. This means Signal can invalidate the link without changing your username — useful if the link gets shared somewhere you did not intend.

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Changing or deleting your username

You can change your username at any time. Changing the nickname resets the discriminator. Any existing signal.me links you previously shared will stop working after you change your username, so anyone who saved the old link will need the new one. To delete your username entirely:
  1. Go to Settings → Account → Username.
  2. Tap Delete username and confirm.
Deleting your username means you can only be reached by people who have your phone number (subject to your discoverability setting).

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How phone number hiding works

When you set Who can find me by number to Nobody, Signal records that preference on its servers. During contact discovery — the process by which Signal checks which numbers in your contact list are registered — your number is excluded from results returned to other users. Signal uses Private Contact Discovery (a system based on Intel SGX enclaves and oblivious RAM techniques) to ensure that the server learns as little as possible about which numbers users are looking up, beyond what is strictly necessary to return results. Your discoverability setting is enforced within this system. Additionally, Signal uses two types of sender certificates for sealed sender messaging:
  • ACI + E164 certificate: includes both your account identifier and your phone number.
  • ACI-only certificate: includes only your account identifier, not your phone number.
When phone number sharing is disabled (the default), Signal uses the ACI-only certificate. This means your phone number is not disclosed even in the cryptographic metadata of messages you send to people who do not already know your number.

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Limitations and trade-offs

People who already have your phone number in their contact list and have previously messaged you will continue to see your account in their conversation list regardless of your discoverability setting.
Signal requires a phone number to register an account. Even if your number is hidden from discovery and you share only your username, your account is still linked to a phone number internally. Signal uses the number to prevent spam registrations and for account recovery.
Your username is visible to anyone you start a conversation with. It is an alias, not a secret. Do not use a username that reveals information you want to keep private.