Sending outbound SMS with the API

Use API v1.1 to send SMS from a cloudnumbering number assigned to your organisation.

Before you start

The sending number must belong to the organisation that issued the access token.
The sending and destination numbers must use E.164 format, including the leading +.
Your balance must cover every SMS part.

For the runnable request, response behavior, message identifier, delivery receipts, and retry guidance, see Send SMS with API v1.1.

What happens next

A successful API response means the message was accepted for sending. It does not confirm delivery to the handset. Use a delivery receipt when your workflow needs the final status.

Each SMS part is charged separately, and one message can contain no more than six parts.

Warning: The send-SMS request has no idempotency key. Do not submit the same message automatically after a timeout or unknown response. The original request might have succeeded, and a retry can send and charge for another message.

Troubleshooting

The request is rejected

Check the access token, E.164 number format, message length, organisation ownership of the sending number, and account balance. See Troubleshooting SMS for symptom-specific checks.

The request succeeds, but the message is not delivered

Check the delivery receipt for the final status. If no receipt arrives, confirm that the original request included a reachable delivery-receipt URL.

The outcome is unknown

Do not submit the same message again automatically. Record the UTC time, masked numbers, and X-Request-Id response header when present, then contact support.