Zernio
Zernio
API Reference

SMS

Messaging

Send an SMS/MMSPOSTLook up carrier + line typeGETList SMS opt-outsGET

Number Setup

Enable SMS on a numberPOSTDisable SMS on a numberDELETEAdd number to SMS registrationPOST

Registrations

List carrier registrationsGETPre-check a carrier registrationPOSTStart a carrier registrationPOSTGet a carrier registrationGETCreate a registration share linkPOSTDeactivate a brand/campaign registrationDELETE

Registration Review

Appeal a rejected campaignPOSTReply to a change requestPOSTUpload opt-in form proof for an appealPOSTUpload opt-in form proofPOSTRe-send the sole-prop OTPPOSTSubmit the sole-prop OTPPOST

Sender IDs

List alphanumeric sender IDsGETCreate an alphanumeric sender IDPOSTDelete an alphanumeric sender IDDELETERequest a higher sender ID daily limitPOST
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SMS

Send an SMS/MMS

Sends an SMS (or MMS when mediaUrls is set) from one of your SMS-enabled numbers. At least one of text / mediaUrls is required. Both numbers are normalized to E.164, so from matches regardless of formatting and replies thread into the same inbox conversation.

US numbers must have an approved carrier registration (/v1/sms/registrations) before messages deliver.

Replies and delivery status arrive as webhooks, not by polling: an inbound reply fires message.received with platform: "sms", the first message of a new thread also fires conversation.started, and this message's own outcome fires message.delivered or message.failed (the latter carrying the carrier's error code).

Opted-out recipients: a send to a number that replied STOP is refused with 409, never silently dropped.

Idempotency: send an Idempotency-Key header to make retries safe: same key + same body replays the original response instead of sending a second message; same key + different body returns 422; a key still in flight returns 409.

POST
/v1/sms/messages

Authorization

bearerAuth
AuthorizationBearer <token>

API key authentication: send your Zernio API key in the Authorization header, prefixed with Bearer.

In: header

Header Parameters

Idempotency-Key?string

Optional client-generated unique key (e.g. a UUID) that makes retries safe. Same key + same body replays the original response; same key + different body → 422; key still processing → 409.

Lengthlength <= 255

Request Body

application/json

TypeScript Definitions

Use the request body type in TypeScript.

Response Body

application/json

application/json

application/json

{  "id": "string",  "conversationId": "string",  "status": "sent"}
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Rotate a SIP trunk's password

Mints a new digest password on the trunk. The old password stops working immediately, so update the destination platform right away.

Look up carrier + line type

Carrier name and line type (mobile / landline / voip / toll-free) for a number, plus `smsReachable` (landlines can't receive SMS). Use it to validate recipients before sending. Each lookup is billed by the carrier-data provider, so call it explicitly (e.g. pre-validating an opt-in list), not on every send.

from*string

One of your SMS-enabled numbers (E.164; formatting is normalized).

to*string

Recipient number (E.164).

text?string

Message body. Required unless mediaUrls is set. Max 10 SMS segments (1530 GSM-7 or 670 unicode characters).

mediaUrls?array<>

Public media URLs to attach (sends as MMS). Max 10.

Itemsitems <= 10
sendAt?string

Optional. Schedule the send for a future time (ISO 8601 with offset, e.g. 2026-08-01T12:00:00Z). Must be in the future. The message is queued and the message.delivered webhook fires when it actually sends.

Formatdate-time