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Changelog

Every change to the API is listed here, newest first, under the day it went live in UTC. Changes within v1 never break working code; see versioning.

2026-10-08

  • OpenAPI descriptions. held and the cancel operation now say that released funds return to your available balance at the next settlement step, within about a minute. The bulk send example no longer asks recipients to reply STOP, since replies are not processed. Requests and responses are unchanged.
  • Developer docs published. This site: a page for every endpoint and every error code, code samples in cURL, Python, Node.js and PHP, and guides.
  • OpenAPI document. Every field and parameter is described, operations are grouped by tag and name the scope their key needs, and each error example is a real response. Requests and responses are unchanged.
  • API v1. Send one SMS, a bulk send or a personalised batch; get, list and cancel messages; read your balance and sender IDs. Idempotency keys, per-organisation rate limits and an OpenAPI document at https://api.messaging.500calls.com/v1/openapi.json.
  • Deprecated: POST /v1/messages. Use POST /v1/sms/messages, which takes the same body. Sunset: 15 April 2027. See the migration guide.