Webhook Events | FormantAI

Webhook targets receive only the events they subscribe to.

Event	Trigger	Typical use
`call.completed`	Call connected and ended successfully.	Save transcript, structured results, duration, and recording URL.
`call.failed`	Call failed during setup or could not connect.	Alert, debug, or mark the attempt failed.
`call.busy`	Recipient line was busy.	Update CRM status and wait for retry policy.
`call.no_answer`	Recipient did not answer.	Schedule follow-up or wait for retry.
`call.socket_failure`	Call connected at telephony layer but voice streaming did not start.	Investigate voice streaming or provider issues.
`call.telephony_failed`	Telephony provider failed after call initiation.	Alert operations and reconcile provider status.
`call.unreachable`	Destination number could not be reached.	Mark number invalid/unreachable or request a new contact.

Event fields

Every event uses the same top-level envelope:

Field	Type	Description
`event_id`	string	Unique ID for this webhook delivery. Use for dedupe.
`event_type`	string	One of the event types above.
`timestamp`	string	ISO 8601 timestamp when FormantAI created the event.
`data`	object	Event-specific payload.

Event handling pattern

1 app.post("/webhooks/formant", async (req, res) => {
2   const event = req.body;
3 
4   await saveEventOnce(event.event_id, event);
5 
6   switch (event.event_type) {
7     case "call.completed":
8       await handleCompletedCall(event.data);
9       break;
10     case "call.no_answer":
11     case "call.busy":
12       await markRetryableAttempt(event.data);
13       break;
14     default:
15       await logCallOutcome(event.data);
16   }
17 
18   res.status(204).send();
19 });