Zernio
Zernio
API Reference

Phone Numbers

Numbers

List phone numbersGETGet phone numberGETPurchase phone numberPOSTResolve a number claimGETRelease phone numberDELETE

Availability

List offerable number countriesGETCheck country availabilityGETSearch available numbersGET

Stock Watches

List stock watchesGETWatch an out-of-stock countryPOSTStop watching a countryDELETE

KYC

Get KYC form specGETSubmit KYCPOSTPre-validate KYC addressPOSTPre-review a KYC packetPOSTUpload a KYC documentPOSTView a KYC document on fileGETCreate a hosted KYC linkPOST

Remediation

Get declined requirementsGETResubmit a declined numberPOSTReply to the regulatory reviewerPOSTRespond to the regulatory reviewer (message + corrections)POST

Porting

Check portabilityPOSTCountry porting requirementsGETPort numbers inPOSTList port-in ordersGETResolve a port claimGETA port-in order's pending requirementsGETUpload a porting documentPOSTCancel a port-inDELETE

Other

Request the WhatsApp verification code for a numberPOST
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Phone Numbers

List offerable number countries

The phone number countries available to purchase, each with its flat monthly price (cents), regulatory tier, whether it needs end-user KYC (Tier 3/4), and per-feature availability (PSTN calls, WhatsApp, SMS, and WhatsApp Business Calling outbound). Drives the country picker. Tier-4 countries appear only when enabled. No API key needed: the catalog is public so you can browse it before you have an account.

GET
/v1/phone-numbers/countries

Response Body

application/json

import Zernio from '@zernio/node';const zernio = new Zernio({ apiKey: process.env.ZERNIO_API_KEY });const { data } = await zernio.phonenumbers.listPhoneNumberCountries();console.log(data);
{  "countries": [    {      "code": "string",      "tier": 1,      "monthlyCents": 0,      "needsKyc": true,      "callsAvailable": true,      "whatsappAvailable": true,      "smsAvailable": true,      "outboundCallingAvailable": true,      "inStock": true,      "preOrderable": true,      "types": [        {          "numberType": "local",          "tier": 1,          "needsKyc": true,          "monthlyCents": 0,          "whatsappAvailable": true,          "smsAvailable": true,          "callsAvailable": true,          "inStock": true,          "fulfilment": "instant",          "preOrderable": true        }      ]    }  ]}
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Release phone number

Release a purchased phone number. This will: 1. Disconnect any linked WhatsApp account 2. Decrement the Stripe subscription quantity (or cancel if last number) 3. Release the number from Telnyx 4. Mark the number as released

Check country availability

Pre-purchase check, so you can warn BEFORE a customer invests in KYC (regulated review is async, 1-3 days). Tells you whether we have deliverable inventory, and what address the customer needs: - `addressConstraint: geo` → the registered address MUST be in one of the returned `areas` (the only place we have stock). A different-area address passes pre-approval but the number can never be assigned. - `addressConstraint: country` → any in-country address works. - `addressConstraint: none` → field-only / instant country, no address. Call this before starting the KYC form for regulated countries. Without an API key it answers from cache only and returns just `country`, `numberType` and `areaOptions`, for building an area picker before signup.