# Webhook

> A webhook is an HTTPS request the gateway sends to your endpoint when something happens (a message is delivered or fails, a reply arrives, the balance runs low), so you do not have to poll for status.

Instead of asking the API repeatedly whether a message has been delivered, you register an endpoint and receive an event when it is. Events carry an id, a type, a timestamp and the data; they are signed so you can verify their origin, and they are retried when your endpoint does not answer.

A production handler verifies the signature, acknowledges within seconds, processes from a queue, deduplicates on the event id and orders by time, because retries and replays deliver the same event more than once and not always in order.

At SMSMeteor: events are signed with HMAC-SHA256 in `X-Meteor-Signature`, retried 6 attempts over 24 hours, and replayable from the panel. See the [webhooks page](https://smsmeteor.com/docs/webhooks).

Related terms: [HMAC signature (webhooks)](https://smsmeteor.com/glossary/hmac-signature), [Delivery receipt (DLR)](https://smsmeteor.com/glossary/delivery-receipt), [Exponential backoff](https://smsmeteor.com/glossary/exponential-backoff), [Request ID](https://smsmeteor.com/glossary/request-id)

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