A webhook is an HTTP callback used by one system to notify another about an event. In an AI phone assistant the canonical use case is: call ended → webhook to CRM with transcript, outcome and contact data.
Compared to API polling, webhooks are efficient (no idle traffic) and near-real-time. The receiving system must expose a publicly reachable endpoint and implement standard webhook hygiene: HMAC signature verification, idempotency, retry handling, and generous timeout tolerance.
Operational pitfalls: transient endpoint outages, out-of-order delivery on retries, and unversioned payload schemas. A solid webhook stack has a dead-letter queue, a UI for manual retriggers, and versioned payload contracts.