Updated 09/17/2026 to reflect the introduction of optional Signal Login, which allows users to register without a phone number

The issue with the phone number. It’s probably one of the most common criticisms you hear about Signal. And that’s saying something. Otherwise, with its focus on security and privacy while maintaining user-friendliness, Signal offers little cause for criticism (we have fact-checked common criticisms and myths about Signal in a separate blog post). However, things have changed. Signal now offers Signal Login, which allows you to optionally register without a phone number.

But why did Signal need a phone number to register in the first place? And now that the optional Signal Login is available, do you still need a phone number?

Here we’ll explain why Signal originally chose phone-number-based registration, what role the phone number still plays, and how Signal Login changes the situation.

How does the registration process at Signal work?

First, the facts. For many years, registering with Signal always required a phone number. This could be either a mobile or landline number. The number was then confirmed during registration with a verification code and linked to your Signal account. You can find details about the traditional registration process on this official support page.

But what was the reason for the decision to require a phone number during registration? Why couldn’t you simply sign up at Signal using an email address or any username?

This is the answer that Signal’s president Meredith Whittaker gave to exactly this question in 2022:

Phone numbers allow people to ‘import’ their social graph into Signal and, more importantly, take it with them if they decide to stop using Signal. The network people bring with them via phone numbers helps people quickly connect with their friends and colleagues. And, of course, that network—the network of people you care about, want to collaborate with, and want to talk to—is at the heart of a functioning messaging service.

This was one of the central reasons behind Signal’s decision to use phone numbers. But things have changed since that explanation was given.

Signal now offers usernames, which allow users to connect without sharing their phone number. And with the introduction of Signal Login, Signal has taken the next step: you can now create a Signal account without providing a phone number.

That means the phone number is no longer a fundamental requirement for everyone who wants to use Signal, although it remains the main way to register and connect with existing contacts.

Signal without a phone number? – Now possible

What would a world look like where Signal wouldn’t require a phone number for registration? For a long time, Signal’s answer was that this would create a significant usability problem. After installing Signal, you simply wouldn’t know which of your friends could be contacted via Signal. Of course you could call all of your friends and ask if they’re on Signal and what their username is. But that’s not really practical for a messenger. And Signal believes that only a practical messenger is a useful and secure messenger. After all, what’s the value of a (theoretically) secure messenger that no one uses? Exactly. That’s why Signal traditionally opted for a compromise: use phone numbers for registration and contact discovery, while protecting those phone numbers as much as possible.

By registering with your phone number, you can get started right away. Everyone who installs Signal can see which of the existing contacts are already on Signal and can immediately start writing secure messages. This explains the great success of Signal. Because unlike many other encrypted messaging apps you can get started right away and your friends are notified that you’re now on Signal as well.

Additionally – as Meredith Whittaker mentions in the quote – this allows you to remain in “ownership” of your social network as much as possible. Assuming Facebook shuts down tomorrow (one can still dream) you’ll lose all your contacts there in an instant. On the other hand if you build a social network based on phone numbers it’s independent of the network provider. So if Signal discontinues its services tomorrow you can at least continue to maintain the contacts you’ve made by phone number and won’t lose them completely.

However, Signal has now found a way to separate the convenience of Signal from the requirement to provide a phone number. With Signal Login, you can register without a phone number. Instead of using a phone number as the registration credential, Signal provides an alternative registration mechanism. This means that the old argument that ‘Signal needs your phone number because otherwise nobody would be able to find you’ no longer applies in quite the same way.

Signal can use phone numbers for the traditional registration process while giving users who don’t want to provide a phone number another option.

Fighting spam

As Signal President Meredith Whittaker confirmed there was another reason why Signal required a phone number for registration: combating spam.

Of course it’s relatively easy to obtain new phone numbers and misuse them for spam purposes in some countries. However, this isn’t as easy or as inexpensive as email addresses for example. Therefore, the phone number requirement also made it easier for Signal to combat spam and thus further increase Signal’s user-friendliness.

And this is one of the biggest challenges Signal had to solve before offering registration without a phone number. Signal Login addresses this by introducing a different form of cost into the registration process. Signal Login requires a one-time payment rather than making phone-number-free registration completely free and unlimited. The payment is not intended to turn Signal into a subscription service. Instead, it provides an additional barrier against automated account creation, spam and abuse while also supporting Signal’s mission as a nonprofit organization.

This is an important distinction. Signal Login does not mean that Signal has simply removed every barrier to creating an account. Instead, the phone number has been replaced as the barrier with another mechanism. For users who don’t want to pay, the traditional phone-number-based registration remains available.

Signal hides phone numbers by default

It’s worth noting that when you use a phone number to register for Signal it doesn’t mean that your phone number is exposed to all other Signal contacts. Since February 2024 Signal hides your phone number from your Signal contacts by default. If you use Signal, your phone number will no longer be visible to everyone you chat with (you can change that setting in the settings of Signal). There is only one exception: People who have your number saved in their phone’s contacts will still see your phone number since they already know it.

So in the end registering with a phone number just leads to one small piece of data: Signal itself knows that this phone number is registered with Signal. But since everything is end-to-end encrypted, that’s where it stops. Your messages, media, profile, your group memberships, who you talk to all this information is encrypted and hidden from Signal. This is even true for your contact list.

Signal doesn’t know your contacts

It seems to be logical: In order to determine which of your contacts are already on Signal, Signal must know your address book, right? If that would be true that would be a serious privacy problem.

Fortunately that is not the case for SIgnal. As Signal states on its support pages:

Signal developed a private contact discovery process that enables Signal clients to efficiently and scalably determine whether the contacts in their address book are Signal users without revealing the contacts in their address book to the Signal service. Once your phone knows which of your contacts is a Signal user, it can optionally notify you when a new contact has started using Signal.

Signal has made a significant technical effort to address this question in order to be user-friendly while protecting your data. Signal founder Moxie Marlinspike has explained the technical details and general considerations in two detailed blog posts. If you’re interested in more detail, you can find them here and here.

Summary

These findings can be summarized as follows: Registering with a phone number brings large benefits and very few drawbacks. But with Signal Login, a phone number is no longer required if you don’t want to provide one.

Benefits of registering with a phone number

• You get the benefits of being able to chat with your existing phone contacts immediately and without the hassle of looking them up manually.
• You own your social contacts and are not dependent on a service with the danger of losing all your contacts if the service shuts down.
• It’s harder to fake profiles and easier for you to confirm that you are actually talking to the people you think you’re talking to.
• It’s harder for spammers to register.

Drawback of registering with a phone number

• Signal knows that this phone number is registered with Signal (and the date it was registered and last connected to the service). But that’s it. Signal doesn’t know your name, your messages, your calls, your profile, your metadata, your groups – not even your contacts.

Benefits of Signal Login

• You can register with Signal without providing a phone number.
• Your Signal account doesn’t have to be associated with your phone number.
• You can still use Signal usernames to connect with other people without sharing your phone number.
• You can register even in countries where SMS or call verification is unavailable or blocked.

Drawbacks of Signal Login

• Signal Login requires a one-time payment.
• You lose some of the convenience of automatically connecting with your existing phone contacts. You can still find them, but they can’t find you in the same way.

So in the end, everybody has to decide which of these things are more important to them. As this article has tried to show, there are certainly many good reasons why Signal originally required a phone number. It made Signal easier to use, helped people connect with their existing contacts, and made it harder for spammers to abuse the service.

But Signal Login changes the situation. A phone number is no longer a fundamental requirement for using Signal. If you value the convenience of phone-number-based registration, you can continue to use it. If you don’t want to provide your phone number to Signal, you now have another option.