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
| Property | Value |
|---|---|
| Message types | SMS (text) and MMS (media) |
| From | Any SMS-enabled number on your team, or an alphanumeric sender ID |
| Number format | E.164, normalized automatically |
| Replies | Thread into the inbox; message.received webhook |
| US requirement | Approved 10DLC or toll-free registration |
| Registration reuse | One approval covers many numbers, with no repeat brand fee |
| Idempotency | Idempotency-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
- Get an SMS-capable number. Not every number can text: search with
sms=true, purchase withwantsSms: true, or port in. - Enable SMS and register. Call
POST /v1/phone-numbers/{id}/sms, then run the US carrier registration. An approved registration you already hold covers the new number with no repeat fee. - Send. Send SMS or MMS, respect opt-outs, and read replies in the inbox. For one-way international sends from a brand name instead of a number, use a sender ID.
In this section
Carrier registration
10DLC and toll-free registration, reuse, and appeals
Sending
Send SMS and MMS, handle opt-outs, and look up numbers
Sender IDs
Branded one-way SMS from a name like ZERNIO
Related
- Send an SMS/MMS: every field of the request.
- Start a carrier registration: 10DLC and toll-free.
- Add a number to an existing registration: reuse an approval.
- List SMS opt-outs: recipients who replied STOP.
- Inbox webhooks:
message.received,message.deliveredandmessage.failed.
Call History & Recordings
List every call across your numbers and both channels with GET /v1/calls, open one call, and fetch a fresh recording URL.
Carrier Registration
Register a US number for SMS with 10DLC or toll-free verification through POST /v1/sms/registrations, reuse an approval on more numbers, and appeal a rejection.