Webhooks

Teler delivers asynchronous events to your HTTPS endpoint as signed POST requests. Use webhooks for state changes you can’t afford to poll for: call lifecycle, stream lifecycle, and recording availability.

Delivery contract

Property	Value
Transport	HTTPS POST, JSON body
Timeout	5 seconds for your response
Success	Any 2xx response
Retry policy	Up to 5 attempts, exponential backoff (immediate to ~30 min)
Ordering	Best-effort per call_id. Use timestamps to reorder.
Idempotency	Each event has a unique ID. Dedupe on receive.
Signing	HMAC-SHA256, see Signing & verification

Configure your endpoint

Webhooks are sent to:

• The Call Status URL on a Voice App, for inbound calls.
• The status_callback_url passed to voice.calls.create(), for outbound calls.
• The Call Status URL on a SIP Trunk, for trunk-routed calls.

Your endpoint must be HTTPS and reachable from the public internet.

Respond fast, process async

Your endpoint must return 2xx within 5 seconds. If you do real work inline, such as database writes, downstream API calls, and slow integrations, you risk timeouts and unnecessary retries.

Every production webhook handler should follow the same shape:

1. Verify the signature
2. Acknowledge with 200 OK
3. Enqueue for async processing

Retries

Non-2xx responses, timeouts, and connection errors are retried with exponential backoff:

Attempt	Delay (approx)
1	immediate
2	+5 s
3	+30 s
4	+5 min
5	+30 min

After 5 failed attempts the event is marked failed (not dropped). Failed events can be redelivered for up to 30 days.

Caution

Retries mean your endpoint will receive duplicate events for the same state change. Always dedupe on the event’s unique ID before mutating state.

Ordering

Events for the same call_id are dispatched in chronological order, but network re-ordering can deliver them out of sequence to your endpoint. Don’t trust arrival order. Use the timestamps inside the event payload (occurred_at on the envelope, answered_at, ended_at, etc.) to reconstruct the lifecycle.

Event categories

Signing & verification HMAC-SHA256 verification, required for any production endpoint.

Call events call.initiated · call.answered · call.completed · call.failed

Stream events stream.initiated · stream.completed

Recording events recording.completed · recording.failed