Send SMS

Direct (transactional) send. One message, one recipient, sent now — order confirmations, shipping notices, password resets, invoices, OTPs. One recipient in, one messageId out, with its own lifecycle — as distinct from an audience send, where the platform resolves a segment and returns a job.

type is required and has no default. transactional waives marketing consent, frequency capping and quiet hours; marketing honours them like any other send. Neither waives hard bounces, spamtraps, the account block list or a soft-deleted contact — consent is a legal question, deliverability is a reputation one.

Auth: server-to-server only. A browser-reachable token that can send from a DKIM-verified customer domain while declaring itself consent-exempt is a different risk class from the rest of this API.

Sending is asynchronous. A 201 means accepted and validated, not delivered — the same contract as Brevo, Postmark, SendGrid and Mandrill. Recipient resolution, suppression, sender verification and template resolution all happen synchronously, so every error you can act on is already a 4xx. Delivery state arrives via GET /messages/{messageId} or delivery webhooks.

type: transactional additionally requires the transactional entitlement on the website (422 not_entitled) and is rate-limited separately from campaign volume.

Content: supply EITHER templateId (+ variables, + language) OR inline content. Both is a 422.

Encoding and segments (GSM7/UCS2, segment count) are the gateway's numbers, not ours — they appear on GET /messages/{messageId} once reported, and as a clearly-flagged estimate from /messages/sms/validate. They are deliberately absent from this 201.

curl --location '/messages/sms' \ --header 'Authorization: Bearer <token>' \ --header 'Idempotency-Key: 0f3e2b1a-7c4d-4e2a-9b11-2f6d8c1a5e30' \ --header 'Content-Type: application/json' \ --data '{ "type": "transactional", "basis": "contract_performance", "to": { "contactId": "string", "clientContactId": "string", "phoneNumber": "string" }, "from": "string", "templateId": 0, "content": "string", "language": "string", "variables": {}, "tags": [ "string" ], "metadata": {}, "sendAt": "string", "createContact": true, "retainBody": true, "event": "string", "permId": "string" }'

{ "messageId": "string", "channel": "email", "type": "transactional", "basis": "string", "status": "queued", "contactId": "string", "to": "string", "scheduledFor": "string", "links": { "self": "string" } }

Request

Responses