Webhooks - Chert FaceTime

In Workers & Lines → Integration, enter the webhook URL and select Update. For a changed URL, configure your receiver with the one-time signing secret, acknowledge setup, then select Update again to assign it to this line. Other lines and existing calls keep their original webhook. A saved URL does not verify delivery.

Event types

Event	Fires when	Notes
`call.incoming`	An inbound call is detected	Your response accepts or declines customer_decides calls within five seconds
`call.started`	The call is answered and media is bridged
`call.ended`	A call ends	Includes duration and terminal_reason
`call.failed`	A call cannot be completed	Includes a named failure reason

Signature verification

Every delivery includes X-Chert-Signature: sha256=<hex>, the HMAC-SHA256 of the raw request body.

const expected = "sha256=" + crypto
  .createHmac("sha256", WEBHOOK_SECRET)
  .update(rawBody)
  .digest("hex");

if (!timingSafeEqual(expected, header)) reject();

Delivery semantics

Delivery is at least once; deduplicate on event_id.
Timestamps are ISO-8601 UTC.
Non-2xx responses retry with backoff.
call.incoming does not retry past its decision deadline and fails closed.