Zernio API Docs

Appearance

SMS ​

Send and receive SMS and MMS from your numbers with POST /v1/sms/messages, with US carrier registration handled through the API.

Send and receive SMS and MMS from your numbers with POST /v1/sms/messages. Replies land in the same inbox as your other channels and arrive as message.received events. In the US a number needs an approved carrier registration before messages deliver; Zernio runs that registration through the API.

Quick reference ​

PropertyValue
Message typesSMS (text) and MMS (media)
FromAny SMS-enabled number on your team, or an alphanumeric sender ID
Number formatE.164, normalized automatically
RepliesThread into the inbox; message.received webhook
US requirementApproved 10DLC or toll-free registration
Registration reuseOne approval covers many numbers, with no repeat brand fee
IdempotencyIdempotency-Key header

Before you start ​

SMS requires usage-based billing. In the US, messages do not deliver from a number until its carrier registration (10DLC or toll-free) is approved; approval is asynchronous, so register early. Every other country sends as soon as SMS is enabled on the number.

How it fits together ​

  1. Get an SMS-capable number. Not every number can text: search with sms=true, purchase with wantsSms: true, or port one in (see Phone Numbers).
  2. Enable SMS and register. Call POST /v1/phone-numbers/{id}/sms, then run the US carrier registration (POST /v1/sms/registrations, 10DLC or toll-free). An approved registration you already hold covers a new number with no repeat fee via POST /v1/phone-numbers/{id}/sms/reuse-registration.
  3. Send. POST /v1/sms/messages sends SMS or MMS; respect opt-outs (GET /v1/sms/opt-outs) and read replies in the inbox. For one-way international sends from a brand name instead of a number, use an alphanumeric sender ID.

What this covers ​

  • Carrier registration. 10DLC and toll-free registration, OTP verification for sole-proprietor filings, reuse across numbers, and appeals for a rejected campaign.
  • Sending. Send SMS and MMS, handle STOP/START opt-outs, and look up number capabilities before sending.
  • Sender IDs. Branded one-way SMS from a name (for example ZERNIO) instead of a number, where the destination country supports it.