What Are Webhooks
                     WEBHOOKS
What Are Webhooks?
Event Webhook App
Call completed HTTP request CRM / DB
A practical introduction to event-driven notifications for 
AI voice automation and connected business systems.
Event happens → notification is sent → your 
application acts.
Letstawk · Real-time voice workflow integrations
◉ Letstawk https://letstawk.ai/
01 · FOUNDATIONS
What is a webhook?
A webhook is an automated message sent from one application to another when a specified event occurs.
01 Event-driven 02 No repeated checking 03 Actionable payload
notification
The sending system detects an event The receiving application does not The HTTP request can include event 
—such as a call completing—and need to keep asking whether details that your application 
sends a message to a configured something changed; it is notified validates, stores, or uses to start 
endpoint. when the event happens. another workflow.
Think of a webhook as a doorbell for software: it rings when something 
important happens.
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02 · THE PROBLEM
Why do webhooks matter?
Polling can work, but repeatedly checking for updates may create unnecessary requests and delays.
Polling: ask again and again Webhooks: react to events
Your application sends requests at fixed intervals, The sending system notifies your endpoint after a 
even when nothing has changed. Updates may wait subscribed event. Your application can respond 
until the next check. without waiting for the next polling cycle.
Fewer unnecessary status requests Event-driven automation
Updates arrive closer to event time Useful for fast follow-up workflows
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03 · WORKFLOW
The four-step webhook workflow
A typical integration connects an event source to an endpoint in your application.
01 Configure an 02 Subscribe to 03 Receive 04 Trigger an 
endpoint events notification action
Provide a URL that can Choose the event types The platform sends event Validate and process the 
receive webhook HTTP your application needs to details to your endpoint. event, then update data or 
requests. monitor. start a workflow.
Design the receiver to acknowledge quickly, process safely, and handle retries or duplicates.
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04 · ARCHITECTURE
How a webhook connects systems
A voice platform emits an event; your endpoint receives the HTTP request and hands the payload to your business logic.
Letstawk Webhook Your endpoint Business app
Voice event HTTP POST Verify + validate CRM / database
Common pattern: event → signed request → validation → queue or business logic → outcome.
Keep secrets off the client side. Receive webhooks on a server-side endpoint over HTTPS.
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05 · AI VOICE USE CASES
Where webhooks help AI voice automation
Turn conversation events into useful business actions without relying on manual monitoring.
Call lifecycle updates Lead qualification Transcript events
Know when a call is initiated, in progress, Trigger sales follow-up when a lead Send conversation records for review, 
completed, or failed. meets defined criteria. search, or summarization.
Meeting events Follow-up automation CRM synchronization
Coordinate scheduling changes with Create tasks, send approved messages, Update customer records with interaction 
calendars and other systems. or route a next step. details and outcomes.
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06 · EVENT EXAMPLES
Call lifecycle events
A call can generate several events. Treat each event as a signal to update state, not as a guarantee that every stage will 
arrive in order.
01 Call initiated 02 Call in 03 Call 04 Call failed
progress completed
Create a pending Update status and show Store outcome, duration, Record the reason and 
interaction record. live activity. and available records. decide whether to retry or 
escalate.
Use a stable call or event identifier to correlate updates and avoid creating duplicate records.
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07 · LEAD QUALIFICATION
From conversation to sales action
A qualification event can route the right context to the right team.
1 · Conversation 2 · Qualification result 3 · Follow-up
An AI voice agent asks approved The platform emits an event with Your application updates the CRM, 
questions and gathers relevant lead the configured qualification creates a task, or routes the lead to 
information. outcome and related metadata. a sales representative.
Keep business rules explicit: define what qualifies as a lead, which fields are required, and who owns the next 
action.
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08 · CONVERSATION DATA
Make conversation records available to connected 
tools
Webhook notifications can tell your systems when data is ready for downstream processing.
Store transcripts or call summaries where your 
team works. Data-handling reminder
Attach outcomes to the correct customer or 
Only process data your application is authorized to 
opportunity. receive. Apply access controls, retention rules, and 
appropriate protections for transcripts and 
Start analytics, quality review, or approved customer information.
summarization jobs.
Keep an audit trail of event IDs and processing 
status.
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09 · RELIABILITY AND SECURITY
Secure webhook delivery
Treat each incoming request as untrusted until you verify its origin and validate its contents.
HTTPS Signature verification
Protect data in transit and use valid TLS configuration. Verify the documented HMAC-SHA256 signature against the 
raw request body and secret.
IP allowlisting Secret management
Use source-IP restrictions as an additional layer where Store signing secrets securely; rotate them and avoid logging 
supported. them.
Verify the current provider documentation for exact signature headers, canonicalization rules, and IP ranges.
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10 · DELIVERY RELIABILITY
Retries, backoff, and failed deliveries
Temporary outages happen. Design the receiver and the sender’s retry behavior to work together.
Exponential backoff Jitter and limits Failure notifications
Retry attempts are spaced Randomized delays can reduce Monitor delivery failures and act on 
progressively farther apart to synchronized retry spikes. Define a documented failure events, such as 
reduce pressure on an unavailable maximum duration and a recovery `webhook.failed` where supported.
endpoint. path.
Letstawk’s supplied reference text describes retries with exponential backoff for up to 72 hours; confirm current limits in its 
documentation.
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11 · RECEIVER DESIGN
Build for duplicate and delayed events
A webhook may be retried, delivered late, or processed after a temporary outage.
Use event IDs or idempotency keys to detect repeats.
Make state transitions safe if an event arrives twice. A practical rule
Acknowledge valid requests quickly, then 
Do not assume events always arrive in chronological process reliably in the background. If 
order. processing fails, use a controlled recovery 
mechanism rather than relying on the sender 
Persist processing status before acknowledging where to know your internal state.
appropriate.
Send slow work to a queue instead of holding the HTTP 
request open.
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12 · OPERATIONS
Test, observe, and troubleshoot
A working endpoint is only the beginning; visibility helps keep the integration reliable in production.
Test payloads
Exercise success, invalid payload, unauthorized request, and slow endpoint scenarios.
Delivery logs
Track event ID, timestamp, status code, latency, and retry count.
Alerting
Alert on sustained failures, rising latency, or a growing queue.
Replay strategy
Define how authorized operators can safely retry or replay events.
Use provider testing tools and delivery logs when available, alongside your own application monitoring.
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13 · CHOOSING A PATTERN
Webhooks vs. polling
Choose the approach that fits the event timing, API capabilities, and operational constraints.
Factor Webhooks Polling
Update timing Event-driven; often near real time Fixed intervals; depends on polling frequency
Request volume Usually fewer checks when events are sparse Repeated requests, including when nothing changes
Complexity Requires a secure, reachable receiver Requires scheduling and state comparison
Best fit Call events, lead results, workflow triggers Periodic syncs or APIs without webhook support
Webhooks are not a replacement for every scheduled sync; some systems benefit from a hybrid approach.
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14 · SCALING PATTERNS
Webhooks can trigger serverless workflows
An endpoint can hand off event processing to cloud functions or a queue-based architecture.
Receive Queue or invoke Update systems
A lightweight HTTP endpoint verifies Pass the event to a queue, worker, Write to a CRM, database, analytics 
the signature and validates the or serverless function for durable service, or approved downstream 
payload. processing. workflow.
Common options include AWS Lambda, Google Cloud Functions, and Azure Functions; design for retries and 
observability.
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15 · DEVELOPER VIEW
What might a webhook payload look like?
Illustrative JSON only — field names and event schemas depend on the provider’s current documentation.
Example event payload
{ How to handle it
  "event": "call.completed",
  "event_id": "evt_example_123",
  "timestamp": "2026-10-16T12:30:00Z", 1. Verify the signature.
  "data": { 2. Validate the event type and required fields.
    "call_id": "call_example_456", 3. Record the event ID.
    "status": "completed", 4. Queue the business action.
    "duration_seconds": 184, 5. Return a suitable HTTP response.
    "qualification": "qualified"
  }
}
Never assume these example fields match a live Letstawk payload; consult the current API documentation.
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16 · IMPLEMENTATION
Webhook implementation checklist
A repeatable checklist helps teams avoid common reliability and security gaps.
Create a stable HTTPS endpoint and protect its secrets.
Subscribe only to the event types your workflow needs.
Verify the documented signature and validate request bodies.
Return promptly; use a queue for longer processing.
Handle duplicate events and out-of-order delivery safely.
Monitor failures, retries, latency, and processing backlog.
Document recovery, replay, and escalation procedures.
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17 · AVOIDABLE MISTAKES
Common webhook pitfalls to avoid
Small receiver-design mistakes can create missed updates, duplicate actions, or security gaps.
Trusting any POST request Doing too much synchronously
Verify authenticity and validate payloads. Acknowledge quickly and move long tasks to a queue.
Ignoring duplicates Logging sensitive content
Use idempotency and event IDs. Minimize payload logging and redact secrets or personal data.
No failure monitoring Assuming exact delivery order
Alert on repeated failures and define a recovery path. Use timestamps, state checks, and reconciliation when needed.
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18 · LETSTAWK
Connect voice events to business workflows
The supplied Letstawk reference describes webhook capabilities for voice lifecycle updates and event-driven automation.
Call lifecycle Lead qualification Transcript events
React to call initiation, progress, Start follow-up when configured criteria are Make conversation records available for 
completion, and failure events. met. downstream processing.
CRM synchronization Delivery reliability Developer operations
Keep customer and interaction details Reference material describes retries and Use testing and delivery logs to investigate 
aligned. delivery-failure notifications. integration issues.
Explore current webhook endpoints, event names, signature rules, and delivery limits in Letstawk’s official documentation.
◉ Letstawk https://letstawk.ai/
19 · ROLLOUT
A practical rollout plan
Start with one event and one action, then expand once the receiver is observable and resilient.
1 · Prototype
Receive a test event and validate the payload.
2 · Secure
Enable HTTPS, signature verification, and secret handling.
3 · Harden
Add idempotency, retries, and queue-based processing.
4 · Observe
Track delivery outcomes, latency, and failure alerts.
5 · Expand
Add more event types and business workflows gradually.
Define success metrics such as delivery success rate, processing latency, and duplicate-action rate.
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KEY TAKEAWAYS
Webhooks turn events into action.
They help connected applications respond to voice interactions without repeatedly polling for 
changes.
Use events to trigger relevant workflows.
Build with 
Secure endpoints and verify webhook authenticity. Letstawk
Explore the Webhooks API 
and create responsive AI 
Design for retries, duplicates, delays, and failures. voice workflows.
Monitor delivery and process events idempotently. letstawk.ai
◉ Letstawk https://letstawk.ai/