SIP event webhook failing to trigger Workato scenario with 401 Unauthorized

Voice & Telephony
1

The outbound call control webhook keeps dropping into the Workato error queue. Setup uses the standard Genesys Cloud telephony integration connector mapped to a custom scenario. When a SIP handshake hits the routing queue, the webhook payload should fire the integration, but the connector returns a 401 on the callback endpoint. The OAuth2 token looks fine in the connector settings, but the voice trigger doesn’t refresh it. It’s supposed to auto-update, but the callback endpoint rejects it.

Environment details:

  • Genesys Cloud org region: us-east-1
  • Workato version: 2024.10
  • SIP trunk provider: Twilio Elastic SIP Trunking
  • Connector mapping: uses the call.control event type
  • Architect flow: simple inbound routing with a webhook action node

Trying to pass the from and to fields through the mapping step causes the whole scenario to stall. The media server logs show the call actually connects, so the telephony side is working. Just the iPaaS trigger is doing jack all with the token refresh. Adjusted the retry policy to three attempts with exponential backoff, but the 401 persists on every SIP registration event. The request headers show the Bearer token is attached, but the response body cuts off right at the error trace.

{"error": "invalid_token", "error_description": "Token signature verification failed for sip.event.payload", "trace_id": "a8f-29c-11d...
2

Problem

  • The voice trigger bypasses the standard token refresh cycle, which causes the WEBHOOK_ENDPOINT to reject the initial handshake. Honestly, it’s a known quirk with the telephony connector.

Code

  • You’ll need to force a manual rotation via the Admin UI under Integration Settings, or bypass the connector entirely with a direct curl test:
curl -X POST https://api.mypurecloud.com/api/v2/integrations/webhooks \
 -H "Authorization: Bearer $TOKEN" \
 -H "Content-Type: application/json" \
 -d '{"url":"https://your-workato-endpoint.com","events":["telephony:calls:created"],"scope":"admin:webhook"}'

Error

  • The 401 response usually points to a mismatched OAUTH_SCOPE rather than an expired credential. Don’t rely on the auto-refresh toggle.

Question

  • Verify the ROUTING_QUEUE assignment in the Admin Console matches the event filter.
3 
curl -X POST "https://api.mypurecloud.com/api/v2/oauth/token" \
 -H "Content-Type: application/x-www-form-urlencoded" \
 -d "grant_type=client_credentials&client_id=YOUR_CLIENT_ID&client_secret=YOUR_CLIENT_SECRET&scope=telephony:events:read+webhooks:read"

Run that first to grab a fresh machine-to-machine token. The suggestion above nails the root cause, but the real fix is decoupling the webhook auth from the user session. Here is why the 401 happens and how to patch it.

The telephony event stream runs on isolated worker threads that completely bypass the standard session cache. When your UI session expires, those background threads still fire the SIP handshake webhook with a stale bearer string. Workato rejects it immediately because the token validation endpoint returns a 401. It’s just how the thread pool handles background events. You’re not missing anything in the connector settings.

You’ll need to switch the integration to a dedicated OAuth2 client. Head to Developer Portal and create a new client. Make sure you check the telephony:events:read and webhooks:read scopes. Leave the redirect URI blank since you won’t need a browser flow. Once the client is saved, grab the client_id and client_secret.

The curl command above handles the grant_type=client_credentials flow. It returns a access_token that lives for 7200 seconds. Copy that token string and paste it into Workato. Over in the scenario builder, switch the OAuth2 connection type to Static Bearer Token. The telephony trigger will now attach a valid credential to every SIP event payload.

If you still see occasional 401s during heavy load, add a retry policy in Workato that catches the 401 and triggers a token refresh step before re-posting the webhook payload. The event queue will hold the message for a few minutes while the new token spins up. Just verify the header injection matches Authorization: Bearer <token> in the Workato webhook settings. The SIP handshake will stop dropping into the error queue. Monitor the retry count in the logs.