A WhatsApp unknown contact is anyone messaging you whose number isn't saved in your phone's contacts. You can ignore them, block and report them from the chat, or save the number if you know the person. For floods of messages from strangers, WhatsApp has a setting called Block unknown account messages under Settings, Privacy, Advanced.
Before you block anyone, there's one thing worth checking. WhatsApp says mobile providers recycle phone numbers, so a name you see in a chat might belong to the old owner of that number, not the person messaging you now.
Why a known name can still be a stranger
WhatsApp shows the name you've saved in your phone's contacts, not a name the other person chose. So if a friend changed numbers years ago and you never deleted their old one, a new owner of that number shows up in WhatsApp under your friend's name. WhatsApp's advice is to delete old numbers from your address book whenever someone switches.
If something about a familiar name feels off, ask a question only the real person would know, or contact them another way before you reply.
What to do with a message from an unknown number
| What's happening | Best move |
|---|---|
| A one-off message from someone you might know | Ask who's messaging before you share anything. Save the number only once you're sure |
| They're rushing you, threatening you or asking you to trust them | Stop replying. WhatsApp lists these as signs of a suspicious message |
| They want a password, a PIN, personal details or a payment | Don't share it. Block and report |
| Lots of messages from different unknown accounts | Turn on Block unknown account messages |
| Calls rather than messages | Use Silence unknown callers instead |
The fuller list of red flags, and the four steps WhatsApp gives for dealing with them, is in WhatsApp scams.
Block unknown account messages
This setting sits under Advanced, so it's easy to miss. With it on, WhatsApp blocks messages from unknown accounts when they go over a high volume, while your contacts can still message you as normal. Blocking stops once message rates return to normal.
- Open WhatsApp and tap Settings.
- Tap Privacy.
- Under Advanced, turn on Block unknown account messages.
Be clear on what it doesn't do. WhatsApp says it won't block all unknown messages, only high volumes of them, and you might be prompted to turn it on if you suddenly get a lot. WhatsApp's help article for this setting is written for Android.
Blocking and reporting an unknown contact
- Reporting without blocking won't stop their messages, calls or status updates. Block as well if you want them gone.
- When you report someone from an individual chat, WhatsApp receives up to five of the last messages they sent you.
- The person isn't notified that you reported them.
- If they come back from new numbers, you can block and report each new number.
- When you block, you can untick Report to WhatsApp if you only want to block.
The steps for each phone are in how to block someone on WhatsApp.
Unknown people in a group you were added to
If you're added to a group with people who aren't in your contacts, WhatsApp makes you message the group before you can tap or click any links in it. That pause is deliberate. You can save someone's number if you know or trust them, but a link from a stranger in a group you didn't ask to join is a good one to leave alone.
Strict account settings: for the very few
WhatsApp also has Strict account settings, a lockdown-style mode. WhatsApp is clear that it's built for the very few people who may be targets of sophisticated cyber attacks, and most people aren't. If you do turn it on, it:
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- Turns on two-step verification and locks security notifications on.
- Turns off link previews and turns on blocking for high volumes of unknown account messages.
- Locks your last seen and online, profile photo, About details and profile links to contacts or a smaller list.
- Lets only known contacts, or that smaller list, add you to groups.
You can only switch it on or off from your primary device, not from WhatsApp Web.
My verdict
When a message from an unknown contact turns up, the right response is usually the boring one: don't engage, block, report. If they keep coming in waves, turn on Block unknown account messages. And spend two minutes deleting old numbers from your contacts, because that's how a stranger ends up wearing a friend's name.
Frequently asked questions
What does unknown contact mean on WhatsApp?
It means the person messaging you isn't saved in your phone's contacts. WhatsApp shows the names you've saved, so a number you haven't saved has no name from you attached.
How do I stop unknown numbers messaging me on WhatsApp?
Turn on Block unknown account messages in Settings, Privacy, Advanced. WhatsApp says it blocks high volumes of unknown messages, not every one, so block and report individual numbers too.
Does someone know if I report them on WhatsApp?
No. WhatsApp says the user isn't notified. WhatsApp receives up to five of the last messages they sent you.
Why does a stranger show up under my friend's name on WhatsApp?
Mobile providers recycle numbers. If you still have your friend's old number saved, the new owner of that number appears under your friend's name.
Can unknown people send me links in WhatsApp groups?
If you're added to a group with people who aren't in your contacts, WhatsApp makes you message the group before you can tap or click links.
