What You Need to Know About the Privacy-Focused Messaging App Signal

Sometimes, you just want to have a private conversation. If you’re talking to someone in person, you can just step into a room or other area where the two of you are alone. But things are a little different if you’re chatting online or over texts. Unless your messages are end-to-end encrypted, they could potentially be accessed by malicious actors, the government or your cell service carrier. An easy step everyone can take to better protect themselves is downloading the encrypted messaging app Signal. 

Signal was released over a decade ago in 2014, and more than 40 million people were using the app for encrypted messaging as of 2022, according to the BBC. 

The app gained a lot of popularity in January, 2021 after WhatsApp, another encrypted messaging app owned by Facebook’s parent company Meta, changed its privacy policy. In the wake of this change, people flocked to Signal, causing a surge of new users and a temporary outage of the app. The app-tracking firm Apptopia reported that Signal was downloaded about 1.3 million times a few days after the policy change.

If you’re new to Signal, or want to learn about the app without downloading it, here’s what you need to know about the encrypted messaging app.

What is Signal?

Signal is an open-source, encrypted messaging app. It’s available on Android and iOS devices, and it’s free to download and use. You can voice or video call others through the app, and you can send payments through the app using the cryptocurrency MobileCoin.

Is Signal secure?

Signal uses end-to-end encryption to protect your messages and calls, which means that only your intended recipient can read your messages and receive your call. That way a third-party or government entity can’t intercept your message. But nothing is absolutely secure. 

In 2023, a group of researchers found a way to figure out a Signal user’s location by measuring the time between sending a message and receiving a notification that a message was delivered. The method had an overall accuracy of about 82%, and could be used to spy on someone’s location.

Does my contact need Signal for the app to work?

Yes, you both need to be using Signal for the app to work. You can’t use Signal to message WhatsApp, for example. 

Does Signal send my number to others?

Not necessarily. The app doesn’t send your phone number to others unless you change the setting so others can see your number. Here’s how to change this setting.

1. Open Signal.
2. Tap your profile in the top-left corner of your screen.
3. Tap Settings.
4. Tap Privacy.
5. Tap Phone Number. 

Under Who Can See My Number, you can tap either Everybody or Nobody. 

From this menu you can also let anyone who has your number see you’re on Signal or hide that you’re on the app. Under Who Can Find Me By Number, tap Everybody or Nobody.

Can I send or receive SMS/MMS messages with Signal?

No. Signal used to support SMS/MMS messages in its Android app, but that functionality was removed in 2022. The company wrote at the time that it was removing this capability to prioritize security and privacy, to ensure people don’t encounter unexpected messaging bills and to create and clear user experience for all Signal users.

Can I use Signal for work or travel?

Yes and yes.

If you use Signal for work, just know that every phone must register with a different number in order to work. And if you’re traveling, the app uses the internet to message and call others. So as long as you are connected to the internet you can use the app instead of your own cell service and potentially incurring roaming fees. 

What are safety numbers and are they important?

Safety numbers are assigned to one-on-one chats in Signal, and these allow you to verify the security of your calls and messages with a contact. Verifying safety numbers is a good way to make sure you’re talking to who you intend to be talking to. Once this number is verified, changes to the number must be manually approved in order to send another message.

Signal will let you know when someone changes a safety number. According to Signal, this could just be a person using a new phone or reinstalling Signal, but if you see the safety number changing a lot there could be other issues. 

Here’s how to view and verify a safety number.

1. Open Signal.
2. Go into a chat.
3. Tap on the chat header or the recipient’s name across the top of the chat. 
4. Tap View Safety Number. 

Then, either scan your contact’s QR code that’s displayed on their screen, or compare the numeric sequence displayed beneath the QR code. If the sequence matches on both yours and your contact’s phones, you can each tap Mark as Verified across the bottom of your screens. If the sequences are different, something is wrong.

Does Signal store or sell my data?

“Signal is designed to never collect or store any sensitive information,” Signal wrote online. 

All your data is stored locally on your device, and since everything in the app is end-to-end encrypted, the Signal service can’t access that data. And because Signal can’t access that data, it can’t sell or monetize your data. 

How do I request and download my account data?

1. Open Signal.
2. Tap your profile in the top-left corner of your screen.
3. Tap Settings.
4. Tap Account.
5. Tap Your Account Data. 

You can either export your data as an easy-to-read text file — Export as TXT — or a machine-readable file — Export as JSON. Tap which kind of file you’d like to export your data as then tap Export Report. 

For more on privacy, check out CNET’s best VPN services, best password managers and best antivirus software.