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POST
Check a UK phone number against TPS and CTPS
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.
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

Errors and retries

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 and rate limits before scheduling checks.

Authorizations

Authorization
string
header
required

Use an Airscale workspace API key. Never expose the key in client-side code.

Body

application/json

Only phone, phone_number, and mobile_phone are accepted; any other field returns 400. Maximum JSON body size: 256 KiB.

phone
string | null
required

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.

Required string length: 1 - 32
phone_number
string | null

Alias used only when phone is null or absent.

Required string length: 1 - 32
mobile_phone
string | null

Alias used only when phone and phone_number are null or absent.

Required string length: 1 - 32

Response

The result of a completed check. Costs one credit whether the number is listed or not.

status
string
required
Allowed value: "success"
phone
string
required

Normalized UK number in +44 format.

Pattern: ^\+44\d{9,10}$
listed
boolean
required

True when the number is on TPS, CTPS, or both.

on_tps
boolean
required

True when the number is on TPS, the UK register for individuals.

on_ctps
boolean
required

True when the number is on CTPS, the UK register for businesses.

result
enum<string>
required

Readable summary of on_tps and on_ctps.

Available options:
Listed on TPS,
Listed on CTPS,
Listed on TPS & CTPS,
Not listed on TPS/CTPS
credits_used
number
required
credits_remaining
number | null
required

Remaining workspace credit balance after the charge.