# Carrier error code

> A carrier error code is the reason attached by the operator to a failed SMS, such as unknown subscriber, absent subscriber, barred or blocked by filter, mapped by gateways to plain-language failure reasons.

Operators return failures as numeric or short codes from their signalling systems. They differ by operator and protocol, so gateways translate them into a dozen stable reasons: unknown number, absent subscriber, barred, filtered, unsupported, network error. The raw code stays available for the cases where a support team needs it.

The reasons decide the action: remove unknown numbers, retry absent ones later, change sender or content for filtered ones, escalate network errors if they cluster on one operator.

At SMSMeteor: every failed message carries both the raw `carrier_code` and a `failure_reason`, in the report, the API and the webhook.

Related terms: [Failed vs rejected](https://smsmeteor.com/glossary/failed-vs-rejected), [Unknown subscriber](https://smsmeteor.com/glossary/unknown-subscriber), [Absent subscriber](https://smsmeteor.com/glossary/absent-subscriber), [Carrier filtering](https://smsmeteor.com/glossary/carrier-filtering)

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Source: https://smsmeteor.com/glossary/carrier-error-code (HTML). Generated by SMSMeteor from the same data as the page. Summary of the whole site: https://smsmeteor.com/llms.txt