Validate international phone numbers
Validate international phone numbers, verify E.164 formats, resolve ITU country mapping, and detect line types (Mobile/Landline/VOIP/Toll-Free/Premium Rate)
Request
- x-api-key: <your-api-key>
- Content-Type: application/json
Response
{
"status": "success",
"valid": true,
"e164": "+48600700800",
"international": "+48 600 700 800",
"national": "600 700 800",
"countryCode": "PL",
"callingCode": "48",
"lineType": "mobile",
"carrier": "Orange Polska",
"tokensDeducted": 1
}What it does
Parses a phone number in any national or international spelling, normalises it to E.164, resolves the country and calling code, and classifies the line (mobile, fixed, VoIP, toll-free). Carrier is by number range, not by a live network query — for that, the HLR endpoint in this group asks the network whether the subscriber is actually reachable.
When to use it
Normalising a contact form before it reaches the CRM; choosing SMS versus voice; deduplicating a customer list.
Request
Body
| Field | Type | Required | Description |
|---|---|---|---|
defaultCountry | string | no | Optional 2-letter ISO country code fallback if no leading "+" or "00" is included (e.g. "US", "GB", "PL") |
phone | string | yes | The phone number string to verify (e.g., "+48 601 234 567", "0014155552671", or "+447911123456") |
Example request
{
"phone": "+48 600 700 800",
"defaultCountry": "PL"
}Response
| Field | Type | Description |
|---|---|---|
isValid | boolean | |
phoneDetails | object | |
↳ countryCallingCode | string | |
↳ countryCode | string | |
↳ countryName | string | |
↳ e164Format | string | |
↳ internationalFormat | string | |
↳ lineType | enum | One of: MOBILE, LANDLINE, VOIP, TOLL_FREE, PREMIUM_RATE, FIXED_LINE_OR_MOBILE, UNKNOWN. |
↳ nationalDestinationCode | string | |
↳ nationalFormat | string | |
↳ rawInput | string | |
↳ rfc3966Format | string | |
↳ subscriberNumber | string | |
status | string | |
tokensDeducted | integer | |
validationResult | object | |
↳ isE164Valid | boolean | |
↳ isLengthValid | boolean | |
↳ reason | string |
Example response
{
"status": "success",
"valid": true,
"e164": "+48600700800",
"international": "+48 600 700 800",
"national": "600 700 800",
"countryCode": "PL",
"callingCode": "48",
"lineType": "mobile",
"carrier": "Orange Polska",
"tokensDeducted": 1
}Errors
Every error answers with the same envelope: an HTTP status, a machine code and a sentence.
400 | The body or a parameter failed validation. The details array names the field. |
401 | No key, a revoked key or a wrong header. Send x-api-key. |
402 | The wallet cannot cover this call. Top up or wait for the monthly grant. |
404 | The resource does not exist, or it is not yours. Both answer identically and cost nothing. |
429 | Over the per-minute quota of your tier. Back off and retry. |
5xx | Upstream refused or timed out. The call is not billed. |
Code
curl -X POST 'https://app.castomapi.com/v1/verify/phone' \
-H 'x-api-key: <your-api-key>' \
-H 'Content-Type: application/json' \
-d '{"phone": "+48 600 700 800", "defaultCountry": "PL"}'const res = await fetch('https://app.castomapi.com/v1/verify/phone', {
method: 'POST',
headers: { 'x-api-key': '<your-api-key>', 'Content-Type': 'application/json' },
body: JSON.stringify({"phone": "+48 600 700 800", "defaultCountry": "PL"})
});
const data = await res.json();
console.log(data);import { request } from 'node:https';
// Node 18+ has fetch built in
const res = await fetch('https://app.castomapi.com/v1/verify/phone', {
method: 'POST',
headers: { 'x-api-key': '<your-api-key>', 'Content-Type': 'application/json' },
body: JSON.stringify({"phone": "+48 600 700 800", "defaultCountry": "PL"})
});
const data = await res.json();
console.log(data);import requests
res = requests.post(
'https://app.castomapi.com/v1/verify/phone',
headers={'x-api-key': '<your-api-key>'},
json={"phone": "+48 600 700 800", "defaultCountry": "PL"},
timeout=30,
)
print(res.json())<?php
$ch = curl_init('https://app.castomapi.com/v1/verify/phone');
curl_setopt_array($ch, [
CURLOPT_CUSTOMREQUEST => 'POST',
CURLOPT_RETURNTRANSFER => true,
CURLOPT_HTTPHEADER => ['x-api-key: <your-api-key>', 'Content-Type: application/json'],
CURLOPT_POSTFIELDS => json_encode(['phone' => '+48 600 700 800', 'defaultCountry' => 'PL']),
]);
$data = json_decode(curl_exec($ch), true);
print_r($data);Cost and limits
This operation needs no API key and costs nothing: called without a key it answers 200 and deducts zero tokens, up to 10 requests a minute per IP address.
Rate limits per minute
| No key | 10 |
| Free | 60 |
| Pro | 300 |
| Enterprise | 1200 |
Questions
What does Validate international phone numbers cost?
This operation needs no API key and costs nothing: called without a key it answers 200 and deducts zero tokens, up to 10 requests a minute per IP address.
How do I authenticate?
Send your key in the x-api-key header. One key covers every metered endpoint; there is nothing to enable per endpoint.
Can I send an Authorization: Bearer token instead?
Not for a metered endpoint — those take the x-api-key header and nothing else. Bearer tokens belong to the account side: the dashboard and account APIs accept a JWT session, and castomapi-auth issues those through a standard OAuth2 handshake, with authorization code, client credentials and refresh grants. The auth service page covers it.
What are the limits?
10 requests a minute per IP with no key at all, 60 a minute on the free tier, 300 on Pro, 1200 on Enterprise. Above the no-key tier the quota is per account, across every endpoint.
OpenAPI: https://app.castomapi.com/docs/json