# Twelve reasons an SMS fails, and what the report tells you

> Unknown numbers, absent subscribers, carrier filters, expired validity: every failure reason in the delivery report, what caused it and what to do next.

Updated 2026-08-28. Level: Intermediate. By SMSMeteor.

## Key takeaways

- A failure carries a raw code and a plain reason.
- Unknown numbers: remove. Absent subscribers: retry later.
- A rising share is a signal; one failure is noise.
- Sent without delivered is not a failure.

## Reading a failure

A failed message carries two things: the raw code the carrier returned and a plain-English reason we map it to. The raw code differs from one operator to the next; the reason is the same everywhere so you can act on it. Both are in the panel, in exports and in the `message.failed` webhook. Failed messages were accepted by a carrier that could not deliver them, so they are billed like any attempt; messages we refuse before sending are rejected and never billed.

## The twelve reasons

- Unknown number. The number is not assigned. Remove it; it will never deliver.

- Absent subscriber. The phone was off or out of coverage for the whole validity period (48 hours by default). Retry in a later campaign.

- Handset or memory full. The phone refused the message. Rare; retry later.

- Blocked by carrier filter. Content or sender flagged by the operator. Check the sender rule and avoid link shorteners on strict routes.

- Ported number. The number moved to another operator and the route did not follow. We re-route automatically; a retry usually delivers.

- Roaming unreachable. The subscriber is abroad on a network that does not accept the message. Retry later or accept the loss.

- Barred subscriber. The line is suspended, often for unpaid bills. Remove after two occurrences.

- Do-not-disturb list. Markets with a national DND registry, such as India, block promotional traffic to registered numbers. Transactional templates pass; marketing does not.

- Invalid sender for route. Prevented before sending in almost every case, because the platform swaps the sender; appears only when replacement is disabled by you.

- Expired. Validity elapsed while the carrier kept retrying. Reported as expired rather than failed; not billed a second time.

- Destination unreachable. A carrier-wide problem, usually visible on the [status page](https://smsmeteor.com/status). Wait for the incident to close; queued messages resume.

- Rejected by operator, no reason. Some operators return a generic code. We flag the pattern per operator; if it repeats, the route is reviewed.

## Patterns worth acting on

One failure is noise; a share is signal. A rising unknown-number share means the list is ageing: clean it from the report with one click. A rising filter share on one operator means the content or sender is being flagged: change the sender type or remove the shortener. A sudden jump across all operators of one country is a route problem, and it is our job: it will be on the status page, usually before you notice.

## What is not a failure

Sent without delivered is not a failure. Some operators return receipts in batches or not at all; the country page says which. And rejected is not a failure either: it is the platform refusing to send something that would have failed, and refusing to bill you for it.

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Source: https://smsmeteor.com/guides/why-sms-fail (HTML). Generated by SMSMeteor from the same data as the page. Summary of the whole site: https://smsmeteor.com/llms.txt