Envelope

Success

{ "data": … }

data is an object or an array, depending on the endpoint. It is wrapped rather than returned bare so that adding a sibling key later — paging cursors, rate-limit state — is additive for you instead of breaking. A bare array leaves nowhere to put those.

Error

{ "error": { "type": "insufficient_scope", "message": "…", "scope": "sms:send" } }

Branch on error.type. See Errors for the catalog.

Status codes

Status	When
200	Success with a body
201	Something was created. A Location header points at it, where one exists.
204	Success with no body — deletes
4xx	Rejected. Nothing was created and nothing was charged.
5xx	Failed on our side. Nothing was charged — which is what makes a retry safe.

Arrays are never null

An empty list is []. Every list field on every response follows this, including nested ones like userIds and skipped. A null where you expect an array is a routine cause of integration crashes, so this API does not produce one.

Note that [] can carry meaning: an empty userIds on an SMS line means everyone, not nobody.

Unknown fields are rejected

A request body with a field this API does not recognize is a 400:

{ "error": { "type": "invalid_request", "message": "malformed request body: json: unknown field \"mesage\"" } }

Silently ignoring "mesage" would leave you debugging a request the server considered perfectly fine. This is deliberate, and it applies to every write.

No customerId anywhere

The credential already determines the account. Nothing echoes an account id back at you, and nothing accepts one — so there is no field to get wrong, and no way to accidentally address someone else's data.