> ## Documentation Index > Fetch the complete documentation index at: https://docs.airscale.io/llms.txt > Use this file to discover all available pages before exploring further. # UK DNC Checker > Check whether a UK phone number is registered on TPS or CTPS. Rate limit: 5 requests per rolling second per workspace. Submit a UK phone number using `phone`. The operation checks the number against the UK TPS and CTPS registers: TPS (Telephone Preference Service) is the register for individuals, and CTPS (Corporate Telephone Preference Service) is the register for businesses. For US numbers, use the [US DNC Checker](https://docs.airscale.io/api-reference/dnc-checker.md). > [!NOTE] > > A completed check costs 1 credit whether the number is listed or not. The limit is 5 requests per rolling second per workspace. Validation failures, rejected numbers, and lookup failures are not charged. ## Send a number Send national (`020 7946 0000`) or international (`+44 20 7946 0000`) format. Spaces, parentheses, dots, and hyphens are accepted, up to 32 characters. Numbers in the Crown dependency ranges, such as Jersey, Guernsey, and the Isle of Man, are accepted. The response returns the number in `+44` format. `phone_number` and `mobile_phone` are accepted aliases. `phone` takes precedence when non-null, followed by `phone_number`, then `mobile_phone`. Any other body field returns `400` with `code: "invalid_input"`. The maximum JSON body size is 256 KiB. ## Read a successful result | Field | Meaning | | - | - | | `status` | `success` for a completed check. | | `phone` | Normalized UK phone number in `+44` format. | | `listed` | `true` when the number is on TPS, CTPS, or both. | | `on_tps` | `true` when the number is on TPS, the register for individuals. | | `on_ctps` | `true` when the number is on CTPS, the register for businesses. | | `result` | `Listed on TPS`, `Listed on CTPS`, `Listed on TPS & CTPS`, or `Not listed on TPS/CTPS`. | | `credits_used` | Credits charged for this check: always `1`. | | `credits_remaining` | Remaining workspace credit balance. | ## Errors and retries | Status | Meaning | Charged | | - | - | - | | `400` | Invalid JSON, a body that is not an object, or an unsupported field. | No | | `401` | Missing or invalid API key. | No | | `403` | Insufficient credits. At least 1 credit is required before a check starts. | No | | `413` | JSON body larger than 256 KiB. | No | | `422` | `code: "unsupported_phone_region"` for a valid non-UK number; `code: "invalid_input"` for a missing, malformed, or invalid UK number. | No | | `429` | Workspace rate limit exceeded. | No | | `502` | The register lookup failed or returned an invalid result. | No | | `503` | A service the check depends on is temporarily unavailable. | No result is returned | | `504` | The register lookup timed out. | No | Correct the input before retrying a `400` or `422`. After `429`, retry in a later second with bounded exponential backoff. For temporary `502`, `503`, or `504` responses, retry with increasing delays and a fixed retry limit; contact support if errors persist. Every completed retry is a new check that costs 1 credit. ## Next step Review [Authentication](https://docs.airscale.io/api-reference/authentication.md) and [rate limits](https://docs.airscale.io/api-reference/rate-limits.md) before scheduling checks. ## OpenAPI ````yaml openapi.json POST /v1/uk-dnc-check openapi: 3.1.0 info: title: Airscale Public API version: '2026-09-11' description: Search, enrich, and resolve public business data with Airscale. x-airscale-source-repository: ViceScale/airscale-code x-airscale-source-sha: 1de19e1b70a052a4b8d9c2075021a7e5e7a94d51 servers: - url: https://api.airscale.io description: Production security: - bearerAuth: [] tags: - name: Search and discovery description: Search people, companies, and the web. - name: Contact data description: Find professional and personal contact data. - name: Profiles and reverse lookup description: Extract profiles or resolve a person from known contact data. - name: Post engagement description: Retrieve and enrich people who liked or commented on LinkedIn posts. - name: LinkedIn content description: >- Search LinkedIn posts, read profile and company feeds, and retrieve profile comments and comment reactions. - name: Account description: Inspect workspace account state. - name: Miscellaneous description: >- Find website technologies and check WhatsApp availability, Meta ads, and email deliverability. paths: /v1/uk-dnc-check: post: tags: - Miscellaneous summary: Check a UK phone number against TPS and CTPS description: >- Checks one UK (+44) phone number against the UK TPS register for individuals and the CTPS register for businesses. A completed check costs one credit whether the number is listed or not. Non-UK and malformed numbers are rejected before the check and are not charged. operationId: checkUkDnc requestBody: required: true content: application/json: schema: type: object additionalProperties: false properties: phone: type: - string - 'null' description: >- Recommended field. A UK number in national (020 7946 0000) or international (+44 20 7946 0000) format, including Crown dependency ranges. At most 32 characters; digits, spaces, parentheses, dots, hyphens, and a leading + only. minLength: 1 maxLength: 32 phone_number: type: - string - 'null' description: Alias used only when phone is null or absent. minLength: 1 maxLength: 32 mobile_phone: type: - string - 'null' description: >- Alias used only when phone and phone_number are null or absent. minLength: 1 maxLength: 32 anyOf: - required: - phone - required: - phone_number - required: - mobile_phone description: >- Only phone, phone_number, and mobile_phone are accepted; any other field returns 400. Maximum JSON body size: 256 KiB. examples: request: value: phone: '+442079460000' responses: '200': description: >- The result of a completed check. Costs one credit whether the number is listed or not. content: application/json: schema: type: object properties: status: type: string const: success phone: type: string pattern: ^\+44\d{9,10}$ description: Normalized UK number in +44 format. listed: type: boolean description: True when the number is on TPS, CTPS, or both. on_tps: type: boolean description: >- True when the number is on TPS, the UK register for individuals. on_ctps: type: boolean description: >- True when the number is on CTPS, the UK register for businesses. result: type: string enum: - Listed on TPS - Listed on CTPS - Listed on TPS & CTPS - Not listed on TPS/CTPS description: Readable summary of on_tps and on_ctps. credits_used: type: number const: 1 credits_remaining: type: - number - 'null' description: Remaining workspace credit balance after the charge. required: - status - phone - listed - on_tps - on_ctps - result - credits_used - credits_remaining additionalProperties: false examples: listed: value: status: success phone: '+442079460000' listed: true on_tps: true on_ctps: true result: Listed on TPS & CTPS credits_used: 1 credits_remaining: 99 notListed: value: status: success phone: '+442079460000' listed: false on_tps: false on_ctps: false result: Not listed on TPS/CTPS credits_used: 1 credits_remaining: 99 '400': description: >- Invalid JSON, a body that is not a JSON object, or a field other than phone, phone_number, and mobile_phone. Not charged. content: application/json: schema: type: object properties: error: type: string code: type: string enum: - invalid_input required: - error - code additionalProperties: true examples: {} '401': $ref: '#/components/responses/Unauthorized' '403': description: >- Insufficient credits. At least one credit is required before a check starts. content: application/json: schema: type: object properties: error: type: string message: type: string code: type: string required: - error additionalProperties: true examples: {} '404': description: Unknown path or method. content: application/json: schema: type: object properties: error: type: string message: type: string code: type: string required: - error additionalProperties: true examples: {} '413': description: JSON body exceeds 256 KiB. content: application/json: schema: type: object properties: error: type: string message: type: string code: type: string required: - error additionalProperties: true examples: {} '422': description: >- invalid_input: missing, malformed, or invalid UK number, including a number rejected by the register lookup. unsupported_phone_region: a valid number outside +44. Not charged; correct the input before retrying. content: application/json: schema: type: object properties: error: type: string code: type: string enum: - invalid_input - unsupported_phone_region required: - error - code additionalProperties: true examples: {} '429': description: Workspace rate limit exceeded. Not charged. content: application/json: schema: type: object properties: error: type: string message: type: string code: type: string required: - error additionalProperties: true examples: {} '502': description: >- The register lookup failed or returned an invalid result. Not charged. content: application/json: schema: type: object properties: error: type: string message: type: string code: type: string required: - error additionalProperties: true examples: {} '503': description: >- Authentication, rate limiting, the register lookup, or credit settlement is temporarily unavailable. No result is returned; after a completed lookup, check your balance before retrying. content: application/json: schema: type: object properties: error: type: string message: type: string code: type: string required: - error additionalProperties: true examples: {} '504': description: The register lookup timed out after 30 seconds. Not charged. content: application/json: schema: type: object properties: error: type: string message: type: string code: type: string required: - error additionalProperties: true examples: {} components: responses: Unauthorized: description: The Bearer token is missing or invalid. content: application/json: schema: $ref: '#/components/schemas/Error' schemas: Error: type: object additionalProperties: true properties: error: type: string message: type: string securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: API key description: >- Use an Airscale workspace API key. Never expose the key in client-side code. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.