Twilio Webhook Monitoring
— Coming Soon

Why do Twilio webhooks fail silently?

Twilio fires and forgets. Your endpoint returns a 500 and Twilio logs it — but nobody tells you.

Every Twilio webhook — whether it is an SMS StatusCallback, a Verify OTP result, a voice call status update, or a Studio flow callback — follows the same pattern: Twilio makes a single HTTP POST to your configured URL and moves on. If your server is down, returns an error, or takes too long to respond, Twilio records the failure in its logs and does nothing else.

There is no email. There is no dashboard alert. There is no retry by default (unlike Stripe, which retries for 72 hours). The failure sits silently in the Twilio Console until you happen to look — or until a user reports that their verification code never arrived, their call was not routed, or their automated SMS journey stopped mid-flow.

The consequences depend on which webhook failed:

• SMS StatusCallback failure — your system thinks a message was sent successfully. Delivery tracking is wrong. Follow-up logic (escalations, re-sends, CRM updates) never fires.
• Verify webhook failure — your backend never receives the OTP verification result. The user is stuck on a spinner or gets an error. Your authentication flow is broken for every user who hits that endpoint while it is down.
• Voice StatusCallback failure — call outcome data never reaches your system. Analytics, billing reconciliation, and post-call workflows are silently corrupted.
• Studio flow callback failure — the automated conversation or IVR flow aborts silently at the step that could not post back. Users are left in limbo.

The common thread: Twilio does its part. Your webhook endpoint is the failure point, and Twilio will not tell you about it.

Which Twilio webhooks are most critical to monitor?

Four webhook types account for the majority of mission-critical failures in Twilio-powered apps.

If your product uses Twilio for authentication (Verify), customer-facing messaging (SMS), or automated conversations (Studio), any one of these failing silently is a P1 incident that your users will discover before you do.

How will Webhook Guardian monitor Twilio webhooks?

The same polling approach we use for Stripe, Shopify, and GitHub — read-only API access, 5-minute cadence, instant Slack or email alert.

1. 01

   Connect via read-only API credentials

   You will provide your Twilio Account SID and an API Key with read-only access to Messages, Calls, and Verify resources. No write access. No ability to send messages or make calls. Credentials stored encrypted using AES-256-GCM.

   # Scopes / permissions needed
   GET /Messages · GET /Calls · GET /Verify/Services
   No write access · Revoke from Twilio Console anytime

2. 02

   We poll delivery logs every 5 minutes

   Every 5 minutes, we query the Twilio Messages API for messages with status undelivered or failed, the Calls API for calls with status failed or busy, and the Verify API for verifications where your webhook endpoint did not respond with 2xx. New failures are upserted to your event log.

   # Polling interval
   every 5 min · Messages + Calls + Verify · All sub-accounts

3. 03

   Alert fires with everything you need to act

   The Slack Block Kit message or email includes: the message or call SID, the failure error code (e.g., 30008 for undelivered, 21610 for blocked), the destination number, the timestamp, and a direct link to the Twilio Console record. No digging required.

   # Example: undelivered SMS
   SID: SM1a2b3c · Error: 30008 · +1555···0192
   StatusCallback: 500 · Twilio Console →

4. 04

   Full audit log, same as other integrations

   Every detected failure is logged with timestamp, resource type (Message/Call/Verify), error code, and your alert delivery status. Retained for 7–90 days depending on your plan. Filter by resource type, date range, or error code.

   # Log entry
   type: Message · SID: SM1a2b… · error: 30008
   alert: Slack ✓ · email ✓ · 2026-05-20T14:32:01Z

How do I monitor Twilio webhook failures right now?

The Webhook Guardian integration is not live yet. Here is the manual approach that covers the period until it is.

Until the integration ships, the only reliable way to catch Twilio webhook failures is to poll the Twilio API yourself on a schedule. Here is what to query and what to look for:

For SMS delivery failures

Poll GET /2010-04-01/Accounts/{AccountSid}/Messages.json with Status=undelivered or Status=failed. Filter by DateSent to only fetch recent results. If the count increases, a StatusCallback was not received or your endpoint errored.

# Twilio Messages API — filter for failures
curl -u $ACCOUNT_SID:$AUTH_TOKEN \
  "https://api.twilio.com/2010-04-01/Accounts/$ACCOUNT_SID/Messages.json?Status=undelivered&PageSize=20"

For voice call failures

Poll GET /2010-04-01/Accounts/{AccountSid}/Calls.json with Status=failed or Status=busy. A call in failed state with a missing StatusCallback URL response means your webhook endpoint was unreachable.

# Twilio Calls API — filter for failed calls
curl -u $ACCOUNT_SID:$AUTH_TOKEN \
  "https://api.twilio.com/2010-04-01/Accounts/$ACCOUNT_SID/Calls.json?Status=failed&PageSize=20"

For Verify webhook failures

Poll GET /v2/Services/{ServiceSid}/VerificationChecks and cross-reference with your own database of completed verifications. Any verification marked approved or canceled in Twilio that does not appear in your local records indicates a missed webhook delivery.

The limitation of the manual approach: it tells you about Twilio-side message/call status but cannot directly confirm whether your webhook endpoint received and acknowledged the callback. For full coverage — knowing the HTTP response your endpoint returned — you need server-side request logging on your own infrastructure.

Twilio webhook monitoring — questions answered