SMS Webhook Retry Logic and Idempotency Patterns
Learn how to build reliable webhook handlers for transactional SMS that survive network failures, duplicate deliveries, and concurrent processing without data corruption.
Author
Notilify Team
The Notilify team writes practical notes for engineers and founders building OTPs, alerts, and transactional messaging into production apps.
Posts by Notilify Team
Best SMS API for Startups: Early-Stage Selection Guide
A practical framework for founders and early-stage engineering teams to evaluate transactional SMS providers based on deliverability, sender identity, webhook reliability, and pricing predictability.
Carrier-Rejected SMS: An Incident Runbook
Use this incident runbook to isolate carrier_rejected SMS failures by sender, route, country, carrier, template, and recipient without causing retry storms.
Why OTP SMS Fails in One Country but Works Elsewhere
Debug OTP SMS failures isolated to one market by checking route type, sender and template alignment, local registration, phone formatting, and delivery evidence.
SMS Sender Registration Failed: What to Check
Fix SMS sender registration failures by checking business identity, use case, consent, sample messages, templates, and number associations.
SMS Failing in One Country or on One Carrier
Debug SMS failures isolated to one country or carrier by separating number, sender, content, route, and downstream-network issues.
SMS Accepted but Not Delivered: Where the Message Failed
An accepted SMS request can still fail downstream. Isolate sender, content, registration, route, carrier, and recipient failures without retrying blindly.
SMS API Error Codes and Support Runbook: A Practical Guide
Map carrier and provider failures to actionable next steps. Get concrete error codes, retry logic, and debugging workflows for OTP, account alerts, and delivery issues.
E.164 Phone Number Formatting for SMS APIs: A Developer's Guide
Learn how to normalize and validate phone numbers in E.164 format before sending transactional SMS. Practical code patterns for OTPs, security alerts, and account notifications.
Why OTP SMS Codes Do Not Arrive
Learn why OTP SMS codes fail, delay, expire, or never reach users, and how to debug verification delivery without guessing.
Account Alert SMS Templates: Best Practices for User Notifications
Practical template patterns for transactional account alerts including OTPs, security notifications, and account activity alerts with implementation guidance for developers.
Vonage vs Notilify: Webhook Simplicity Comparison
How Notilify simplifies event-driven SMS workflows compared to Vonage's platform architecture, for teams building critical notification systems.
SMS Support Runbook for Failed Account Alerts
Give support teams a clear runbook for failed account alerts, OTPs, delivery notifications, and security-critical SMS messages.
SMS Webhook Payload Examples for Delivery Tracking
Review SMS webhook payload examples for accepted, sent, delivered, failed, expired, duplicate, and out-of-order delivery events.
How to Debug SMS Delivery by Country and Carrier
Use country, carrier, sender identity, route, and webhook evidence to debug SMS delivery failures without guessing.
SMS Delivered vs Sent vs Accepted: Status Meaning
Learn what SMS accepted, sent, delivered, delivery completed, failed, expired, and unknown mean before building status callbacks.
Two-Factor Authentication SMS Implementation: A Technical Guide
A practical developer guide for implementing 2FA with SMS, covering API integration, code patterns, delivery handling, and operational considerations for production systems.
Sender ID Registration Guide
A scheduled guide for sender identity requirements, approval workflows, and country-specific sender ID expectations.
SMS Pumping Fraud Prevention: Protecting Your OTP Flows
Learn how to detect and prevent SMS pumping fraud in your OTP and verification flows without blocking legitimate users.
SMS Deliverability Troubleshooting by Country and Carrier
A support-ready troubleshooting guide for delayed, filtered, failed, and unknown SMS delivery states.
A2P 10DLC for Transactional SMS Apps
An operational guide to A2P 10DLC registration, campaign details, throughput, and filtering for US transactional SMS.
Transactional SMS API: Send Account Alerts, OTPs, and Track Delivery
Send OTPs, account alerts, and product notifications with a transactional SMS API built for delivery tracking, webhooks, and audit trails.
OTP SMS Delivery Best Practices: Test Delivery and Fix Delays
Test OTP SMS delivery with resend windows, fallback methods, rate limits, anti-abuse controls, templates, and delivery tracking.
Reliable SMS Webhooks and Status Callbacks by Country
Compare SMS APIs for reliable delivery webhooks, status callbacks, retry behavior, and country-level delivery tracking in countries like Spain.