What happened
The phone number already has as many messages waiting as it can hold.
How to fix it
Wait for Retry-After seconds, then retry with the same idempotency key. queue.remaining on GET /v1/phone-numbers shows current room.
This error is safe to retry. Wait for the Retry-After header when it is present. If the endpoint takes an Idempotency-Key, reuse the same key so a retry never creates a duplicate.
Example response
An illustrative example. The message wording and the contents of details vary; branch on error.code.
Still stuck?
Email support@blujay.io with the trace_id from the error response. See Errors for the response format.