# Block a customer (/docs/api-reference/whatsapp/addWhatsappOptOut) > Stop every message you start to this customer from this number, until the block is lifted. The response is 201 when the block is new and 200 when the customer was already blocked, in which case the entry is returned unchanged. > **Set up WhatsApp first.** Connect a WhatsApp number in the dashboard or with [Connect numbers](/docs/api-reference/whatsapp/importWhatsappNumbers). Included on every paid plan. [See plans](https://omnidim.io/pricing). **POST** `/whatsapp/numbers/{number_id}/opt_outs` Stop every message you start to this customer from this number, until the block is lifted. The response is `201` when the block is new and `200` when the customer was already blocked, in which case the entry is returned unchanged. ```yaml operationId: addWhatsappOptOut parameters: - in: path name: number_id required: true schema: type: integer description: | Id of a WhatsApp number in your workspace, from [listWhatsappNumbers](/docs/api-reference/whatsapp/listWhatsappNumbers). A number in another workspace answers `404`. requestBody: required: true content: application/json: schema: type: object required: - customer properties: customer: type: string description: The customer's number in international format, such as `+15551234567`. note: type: string maxLength: 500 description: A note for your team. example: customer: '+15551234567' note: Asked to stop on the call. responses: '200': description: The customer was already blocked. content: application/json: schema: type: object properties: id: type: integer phone_number_id: type: integer customer: type: string example: '+15551234567' source: type: string enum: - instructed_keyword - template_stop_button - meta_marketing_optout - manual description: | How the opt-out happened. `instructed_keyword` and `template_stop_button` are the customer's own and only they can lift them. `meta_marketing_optout` is a marketing choice made in WhatsApp. `manual` is one you added. active: type: boolean opted_out_at: type: string nullable: true opted_in_at: type: string nullable: true description: When a lifted opt-out was lifted. note: type: string nullable: true '201': description: The block was created. content: application/json: schema: type: object properties: id: type: integer phone_number_id: type: integer customer: type: string example: '+15551234567' source: type: string enum: - instructed_keyword - template_stop_button - meta_marketing_optout - manual description: | How the opt-out happened. `instructed_keyword` and `template_stop_button` are the customer's own and only they can lift them. `meta_marketing_optout` is a marketing choice made in WhatsApp. `manual` is one you added. active: type: boolean opted_out_at: type: string nullable: true opted_in_at: type: string nullable: true description: When a lifted opt-out was lifted. note: type: string nullable: true '400': description: >- A bad parameter or body. `code` says which, such as `invalid_parameter`, `invalid_json`, `invalid_limit` or `invalid_cursor`. content: application/json: schema: type: object description: | The error envelope for every WhatsApp route. Some errors add keys: `fields` (the template parameters a send still needs), `ref` (a 500's support reference) and `failed` (on `import_failed`). properties: error: type: string description: Machine-readable category, such as `invalid_request`. error_description: type: string description: Human-readable explanation. code: type: string description: Stable, specific reason, such as `window_closed`. request_id: type: string description: >- Correlates this response with the server log. Also sent as the `X-Request-Id` header. fields: type: array items: type: string description: >- On a template send missing parameters (`missing_fields`), the field keys you still need. ref: type: string description: On a `500`, the reference to quote to support. failed: type: array items: type: object properties: phone_number_id: type: string message: type: string example: >- This WhatsApp number is already connected to another account. Disconnect it there first, then import it again. Contact support if you cannot access that account. description: On `import_failed`, each number and why it could not be connected. example: error: invalid_request error_description: limit must be a whole number from 1 to 100. code: invalid_limit request_id: req_4a1c7d9e2f60 '401': description: Missing or invalid API key. content: application/json: schema: type: object description: | The error envelope for every WhatsApp route. Some errors add keys: `fields` (the template parameters a send still needs), `ref` (a 500's support reference) and `failed` (on `import_failed`). properties: error: type: string description: Machine-readable category, such as `invalid_request`. error_description: type: string description: Human-readable explanation. code: type: string description: Stable, specific reason, such as `window_closed`. request_id: type: string description: >- Correlates this response with the server log. Also sent as the `X-Request-Id` header. fields: type: array items: type: string description: >- On a template send missing parameters (`missing_fields`), the field keys you still need. ref: type: string description: On a `500`, the reference to quote to support. failed: type: array items: type: object properties: phone_number_id: type: string message: type: string example: >- This WhatsApp number is already connected to another account. Disconnect it there first, then import it again. Contact support if you cannot access that account. description: On `import_failed`, each number and why it could not be connected. example: error: unauthorized error_description: Missing or invalid API key code: invalid_api_key request_id: req_6e2b9d4f1a38 '403': description: | `feature_not_enabled` when your plan or role cannot use WhatsApp, `permission_denied` when the key's user cannot make changes, or `service_unavailable` when the account is on hold. content: application/json: schema: type: object description: | The error envelope for every WhatsApp route. Some errors add keys: `fields` (the template parameters a send still needs), `ref` (a 500's support reference) and `failed` (on `import_failed`). properties: error: type: string description: Machine-readable category, such as `invalid_request`. error_description: type: string description: Human-readable explanation. code: type: string description: Stable, specific reason, such as `window_closed`. request_id: type: string description: >- Correlates this response with the server log. Also sent as the `X-Request-Id` header. fields: type: array items: type: string description: >- On a template send missing parameters (`missing_fields`), the field keys you still need. ref: type: string description: On a `500`, the reference to quote to support. failed: type: array items: type: object properties: phone_number_id: type: string message: type: string example: >- This WhatsApp number is already connected to another account. Disconnect it there first, then import it again. Contact support if you cannot access that account. description: On `import_failed`, each number and why it could not be connected. example: error: forbidden error_description: You do not have permission to make changes to WhatsApp. code: permission_denied request_id: req_9f2c1a4b7d3e '404': description: | No number, conversation, message, template, media upload, agent, campaign, contact or opt-out with that id in your workspace. `code` says which. Another workspace's id gives the same answer. content: application/json: schema: type: object description: | The error envelope for every WhatsApp route. Some errors add keys: `fields` (the template parameters a send still needs), `ref` (a 500's support reference) and `failed` (on `import_failed`). properties: error: type: string description: Machine-readable category, such as `invalid_request`. error_description: type: string description: Human-readable explanation. code: type: string description: Stable, specific reason, such as `window_closed`. request_id: type: string description: >- Correlates this response with the server log. Also sent as the `X-Request-Id` header. fields: type: array items: type: string description: >- On a template send missing parameters (`missing_fields`), the field keys you still need. ref: type: string description: On a `500`, the reference to quote to support. failed: type: array items: type: object properties: phone_number_id: type: string message: type: string example: >- This WhatsApp number is already connected to another account. Disconnect it there first, then import it again. Contact support if you cannot access that account. description: On `import_failed`, each number and why it could not be connected. example: error: not_found error_description: WhatsApp number not found. code: number_not_found request_id: req_2c8e7a1d9b40 '500': description: Something went wrong on our side. Quote `ref` to support. content: application/json: schema: type: object description: | The error envelope for every WhatsApp route. Some errors add keys: `fields` (the template parameters a send still needs), `ref` (a 500's support reference) and `failed` (on `import_failed`). properties: error: type: string description: Machine-readable category, such as `invalid_request`. error_description: type: string description: Human-readable explanation. code: type: string description: Stable, specific reason, such as `window_closed`. request_id: type: string description: >- Correlates this response with the server log. Also sent as the `X-Request-Id` header. fields: type: array items: type: string description: >- On a template send missing parameters (`missing_fields`), the field keys you still need. ref: type: string description: On a `500`, the reference to quote to support. failed: type: array items: type: object properties: phone_number_id: type: string message: type: string example: >- This WhatsApp number is already connected to another account. Disconnect it there first, then import it again. Contact support if you cannot access that account. description: On `import_failed`, each number and why it could not be connected. example: error: server_error error_description: >- Something went wrong on our side. Please try again shortly, or contact support with reference 9a1f3e8b02c4. ref: 9a1f3e8b02c4 code: server_error request_id: req_9a1f3e8b02c4 ``` **curl** ```bash curl -X POST "https://backend.omnidim.io/api/v1/whatsapp/numbers/{number_id}/opt_outs" \ -H "Authorization: Bearer $OMNIDIM_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "customer": "+15551234567", "note": "Asked to stop on the call." }' ```