# Validity period

> The validity period is how long a carrier keeps trying to deliver an SMS to an unreachable phone before giving up and marking it expired; a gateway lets you set it per message.

When a phone is off or out of coverage, the SMSC stores the message and retries. The validity period caps that: after it elapses, the message is discarded and reported as expired. Carriers accept values from minutes to days; the useful value depends on the content. A one-time code has no value after ten minutes; a delivery notice is fine for a day.

Setting validity short on codes avoids delivering a stale code that confuses the user and creates a support ticket.

At SMSMeteor: the default validity is 48 hours, settable per message with the `validity` parameter in minutes, up to 72 hours.

Related terms: [Expired message](https://smsmeteor.com/glossary/expired-message), [SMSC](https://smsmeteor.com/glossary/smsc), [OTP (one-time password)](https://smsmeteor.com/glossary/otp), [Absent subscriber](https://smsmeteor.com/glossary/absent-subscriber)

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