Signal is an encrypted chat solution that focuses on privacy, but the first thing it asks for, right after registration, is access to all contacts on the phone. But What does Signal really do with these contacts?
How Signal works is based on phone numbers. You need a phone number to register. This phone number identifies you with Signal. If someone knows your phone number, they can send you a message on Signal. If you send a text message to someone on Signal, they will see your phone number. You cannot use Signal without revealing your phone number to the people you call. In other words, Your “reference address” is your phone number. The only way to get around this feature is to register with a secondary phone number.
Like other modern chatting apps, Signal requires access to contacts on iPhone or Android phone. Signal uses contacts to find other known people who are already using Signal. So you don’t have to ask everyone you know whether or not they use Signal. If a phone number in your contacts is associated with a Signal account, the app will allow you to call it. Signal is designed to be an easy-to-use application that can quickly replace SMS.
This means that by accessing the Contacts, by clicking on “New Message” in the application, you will only see the list of known people who are already using Signal.
When you register, Does Signal let others know this?
When you register with Signal, people who have your number in their contacts will see a message informing them of your subscription and access to Signal.
This message is not sent by Signal and will appear even if you do not grant Signal access to your contacts. Signal just wants people to know that they can now contact you through the app.
Does Signal upload your contacts to its servers?
Some chat apps actually upload your contacts to service servers, store them and use them to connect you with other people you know. So the question is legitimate: Does Signal also upload and store all of your contacts forever?
No, Signal does not store this information.
Signal periodically sends severed phone numbers in encrypted form to discover contacts. Names are never transferred and information is not stored on the servers. The server responds with contacts from Signal users then immediately ignores this information. This way, your phone knows which of your contacts is already using Signal and warns you when your contact starts using the service.
What if you do not grant access to your contacts?
If you don’t feel comfortable granting Signal access to your contacts, the app will still work, a little differently, without some useful amenities.
If you don’t give Signal access to your contacts, the app won’t know who you know. You will have to wait for these people to call you, use the “search by phone number” search function, or type in someone’s phone number to contact them.
How will you know that the other person is using Signal? You might have to ask them first using another chat service. This is why Signal offers contact discovery: instead of talking about using the service in another chat app, you can go directly to speaking on Signal, even if you have no idea that this person is registered there.
When you call someone for the first time, you will only see their phone number. This is because Signal profiles are encrypted and a key shared only with your contacts. This ensures that people cannot determine the name associated with a specific phone number by searching for it on Signal.
Signal works best with access to contacts
Ultimately, Signal is designed to work best when it is granted access to contacts. It is designed as an instant alternative to SMS.
Of course, you can use the service without giving them access to contacts, but that will make it difficult to find and contact people you know.
However, it is possible to grant Signal access to your contacts later: go to your smartphone settings and allow the app to access your contacts.
- On an iPhone: Settings -> Privacy -> Contacts or Settings -> Signal.
- On Android: Settings -> Apps and notifications -> Signal -> Permissions.