How to Block a Number on WhatsApp Business and the API

Yes, a business can block someone on WhatsApp. In the WhatsApp Business app, open the chat, tap the menu, then More › Block, and confirm. On the WhatsApp Business API there’s no button: Meta offers a Block Users API, and it only works on people who messaged you in the last 24 hours. A blocked person can’t message or call you, and you can’t message them.

Which one you use depends on where your number lives. This guide covers the app, unknown numbers, the API’s rules and errors, what the Block contact option in Automate AI does (and doesn’t do), and when an opt-out is the better choice.

Four kinds of “block” on WhatsApp

People mean different things by “block a number”, and each works differently:

The last one is a different problem. If customers are blocking your number, read how to reduce WhatsApp blocks and spam reports.

How to block a number in the WhatsApp Business app

These are the steps WhatsApp’s Help Center gives for Android. Labels can differ a little between versions and on iPhone, so look for Block in the chat’s menu.

From the chat

1. Open Chats and tap the chat with the number.
2. Tap the three-dot menu, then More › Block.
3. Leave Report to WhatsApp ticked if the messages are spam or abuse, or untick it to block only.
4. Tap Block to confirm.

From Settings

1. Tap the three-dot menu, then Settings.
2. Go to Privacy › Blocked contacts (on some versions, Privacy › Contacts › Blocked accounts).
3. Tap the add icon and pick the contact.

Blocking doesn’t delete the chat or remove the person from your phone’s contacts. The chat stays in your list with a note that you blocked them, which they can’t see. They can no longer call or message you, or see your last seen, online status, status updates or profile photo changes. If you share a group, you’ll still see each other’s messages there.

Blocking unknown numbers

A business gets plenty of messages from numbers that aren’t saved. To block one, open the chat and use More › Block, or tap Block on the “Not a contact” notice that WhatsApp shows in a chat with an unknown number. Two settings help when unknown numbers become a nuisance:

Neither setting blocks every unknown number, and that’s deliberate. For a business, most new customers are unknown numbers. WhatsApp’s Help Center doesn’t say whether the first setting is in the WhatsApp Business app, so check your own Privacy settings.

Blocking on the WhatsApp Business API

An API number has no phone app, so blocking is an API call. Meta’s Block Users API lets you block, unblock and list blocked people for one business phone number. The rules:

A developer with access to the number’s token does it like this:

1. Send POST /<PHONE_NUMBER_ID>/block_users with messaging_product: "whatsapp" and a block_users list of the numbers to block.
2. Read the reply: added_users lists who was blocked and failed_users lists who wasn’t. Results are per number, so some can fail while others succeed.
3. To unblock, send DELETE to the same endpoint with the same body. To see the list, send GET, which pages through results with cursors.

The 24-hour rule is the one that surprises people. You can’t pre-load a list of known spammers. You block someone in response to a message they sent. Meta’s reference shows unblocking can fail with the same error for people who haven’t messaged recently.

What Block contact does in Automate AI

In Automate AI, open the chat and choose Block Contact from the chat menu, or use Block contact in the contact panel. From the chat menu you confirm first. You can also tick Block this number when you Mark as irrelevant a chat. While a contact is blocked:

• Their incoming messages are ignored. They don’t appear in the inbox and don’t start chatbots, auto-replies or AI replies.
• You can’t reply from the inbox. The chat shows a red Contact is blocked bar instead of the message box, and automatic replies, AI follow-ups and AI Connections skip them.
• It’s easy to undo. Choose Unblock in the same bar or menu. The chat’s activity timeline records each block and unblock.

A blocked contact isn’t removed from a campaign audience or drip sequence automatically, so take them out of those groups too, or opt them out. Not messaging people who don’t want to hear from you helps keep your quality rating healthy. Contacts, groups and statuses are covered in WhatsApp CRM, and campaigns in WhatsApp marketing.

Block, opt out or just archive?

Blocking is a heavy tool. Use it for people you never want to hear from, not for customers who want fewer messages.

In Automate AI, a typed STOP or unsubscribe opts a contact out automatically, and so does an opt-out keyword you add in Settings › General; button taps don’t. An opted-out contact can still message you. The full process is in WhatsApp opt-outs and unsubscribe requests.

How to unblock a number

• Business app: go to Settings › Privacy › Contacts › Blocked accounts (or Blocked contacts), tap the person, then Unblock.
• API: send DELETE /<PHONE_NUMBER_ID>/block_users with their number. If they haven’t messaged you in 24 hours it can fail with error 131047.
• Automate AI: open the chat and tap Unblock in the red bar, or choose Unblock Contact from the chat menu.

Unblocking doesn’t bring back messages sent while they were blocked. To start a conversation again on the API outside the 24-hour window, you need an approved template and their opt-in. See the 24-hour window.

If a customer blocks your business

Customers can block a business from its chat: tap the business name, then Block business, and pick a reason. After that they can’t message you and you can’t message them. Only they can remove the block; you can’t unblock yourself.

WhatsApp doesn’t tell you who blocked you. On the API, a rise in blocks can lower your number’s quality rating, so a rise in blocks is a reason to look at who you’re messaging and how often. That’s covered step by step in how to reduce WhatsApp blocks and spam reports.