Question 1

Does the API check whether a phone number is actually in service?

Accepted Answer

No. Validation is ruleset-based: it checks that a number is well-formed and assigned under the national numbering plan (libphonenumber metadata). It does not perform live carrier, HLR or number-portability lookups, so it cannot tell whether a line is currently active.

Question 2

Which formats can I send numbers in?

Accepted Answer

Send numbers in E.164 form with a leading + (e.g. +4915123456789), or in national form (e.g. 01512 3456789) together with the country query parameter as an ISO 3166-1 alpha-2 code such as DE or US. Spaces, dashes and parentheses are tolerated.

Question 3

What does the response contain?

Accepted Answer

Each result includes valid and possible flags, the detected line type (MOBILE, FIXED_LINE, TOLL_FREE, VOIP, ...), the ISO country code, the country calling code, and four formatted variants: e164, international, national and rfc3966. Invalid numbers include a reason such as TOO_SHORT or NOT_A_NUMBER.

Question 4

How many numbers can I validate in one batch request?

Accepted Answer

POST /validate/batch accepts up to 100 numbers per call. Results are returned in the same order as the input. Each batch request counts as one API call against your plan.

Question 5

Why do invalid numbers return HTTP 200?

Accepted Answer

An invalid number is a normal, expected result, not an error, so the API returns 200 with valid:false and a reason. HTTP 4xx codes are reserved for malformed requests: a missing number parameter, a batch larger than 100 items, or a JSON body that cannot be parsed.

Question 6

Which countries are supported?

Accepted Answer

All regions with an ITU-assigned country calling code, currently more than 240. Call GET /regions to retrieve the full list of supported ISO country codes and their calling codes.

Question 7

How up to date is the numbering data?

Accepted Answer

The API uses libphonenumber metadata, the same rules used by Android and many telecom applications. The data set is updated regularly as national numbering plans change.

Question 8

What is the difference between valid and possible?

Accepted Answer

possible means the number has a plausible length for its country; valid additionally means it matches the national numbering-plan pattern for an assigned range. A number can be possible but not valid (for example, a correct length in an unassigned prefix).

Phone Number Validator and Formatter

Frequently Asked Questions