Send a broadcast message to multiple recipients

post

https://platform.textingline.com/api/v1/messaging/broadcast

Sends the same SMS or MMS message to a large list of recipients in a single API call. The recipients array must contain between 100 and 50,000 entries with unique phone numbers. The sender number (from) must be an active number assigned to your account. For SMS, provide a body (max 640 characters). For MMS, provide a mediaUrl pointing to a publicly accessible media file; the media is downloaded, validated, and attached to every message in the broadcast. You may include both body and mediaUrl for MMS with text. The broadcast is queued as a background job — the response includes a broadcast id and initial status of queued. An optional idempotencyKey prevents duplicate broadcast submissions.

Content compliance: Message content is validated against messaging compliance rules (SHAFT, phishing, etc.). Messages that violate these rules are rejected with error code 33019.

Rate limit: 5 requests per 60-second window. Every response includes X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset headers. When the limit is exceeded, a 429 response is returned with a Retry-After header.

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Body Params

recipients

array of objects

required

length between 100 and 50000

List of recipients. Each phone number must be unique — duplicate to values are rejected.

recipients*

from

string

required

Sender phone number in E.164 format

body

string

length ≤ 640

Message body text. Required for SMS (when mediaUrl is not provided).

mediaUrl

string

Publicly accessible URL to a media file. When provided, the message is sent as MMS. The file is downloaded, validated, and attached to every message in the broadcast. Maximum file size: 1 MB. Supported types: image/jpeg, image/png, image/gif, video/mp4, video/mpeg, audio/mpeg, application/pdf, text/vcard, text/x-vcard.

idempotencyKey

string

length between 2 and 100

Idempotency key to prevent duplicate sends. Must be 2-100 characters long. Allowed characters: English letters (A-Z, a-z), digits (0-9), and : @ - _ ) (.

Responses

201Broadcast accepted and queued for delivery.

401Unauthorized. Error code 33001 — invalid or missing Basic Auth credentials.

402Payment Required. Error code 33023 — insufficient credits to send the broadcast.

409Conflict. Error code 33013 — a broadcast with the same idempotencyKey is currently being processed.

413Payload Too Large. Error code 33014 — the media file exceeds the maximum allowed size.

429Too Many Requests. Possible error codes: 33002 Rate limit exceeded — you have exceeded the API rate limit. 33012 Daily quota reached — your account has reached its daily messaging quota.

500Internal Server Error. Possible error codes: 33000 Unexpected error — an unexpected error occurred. 33007 Message send failed — the broadcast job could not be created.