Key Takeaways
- android sms gateway troubleshooting webhook timeout: your endpoint did not respond in time. The SMS may already have left the SIM.
- Verify X-SmsGateway-Signature (HMAC) on every POST. Slow handlers still must auth first.
- Return 2xx quickly; enqueue work. Do not hold the callback on a database lock.
- Retries will replay the event. Handlers must be idempotent on message id.
- Priced by devices and SMS send volume. You use your own phone and operator SMS credit. Webhook timeouts do not refund operator SMS.
- Free 300 SMS lifetime is enough to rehearse callbacks on a staff number.
On-call googling android sms gateway troubleshooting webhook timeout usually has an endpoint that talks to four services before it returns 200. The pillar is SMS webhooks. This spoke is latency and retries. Live events: docs.
Priced by devices and SMS send volume. You use your own phone and operator SMS credit.
If signature verification is the last line in a 12-second handler, attackers and retries both get a free window. Verify first. Enqueue second. Sleep never.
Timeout is usually your HTTP handler
Events include message.delivered, message.failed, message.received. Confirm the set in OpenAPI. A slow customer CRM inside the request path is the classic outage — not the Android.
Webhook vs radio vs client
| Symptom | Layer | Fix |
|---|---|---|
| Callback 504 / timeout in our logs | Your HTTPS endpoint | Ack + queue; raise timeout only as a last resort |
| No callback, SMS arrived | URL, TLS, firewall | Public HTTPS; cert; allowlist |
| Duplicate OTP emails/SMS side effects | Retry + non-idempotent handler | Dedupe on event/message id |
| SMS never sent | Phone / airtime | Not a webhook timeout — see carrier rejected |
Ack fast, work async
Target tens of milliseconds for signature check + enqueue. Push CRM, Slack, and warehouse writes off the request. Timeouts will retry; a slow success that still duplicates is worse than a fast 200.
Verify HMAC before you trust the body
X-SmsGateway-Signature = v1=hex(HMAC-SHA256("{timestamp}.{body}", secret)) — re-read docs if the scheme changes. Reject stale timestamps. Sample pattern lives in PHP HTTPS samples, not as a packaged SDK.
Retries will duplicate without idempotency
Store processed event ids. OTP side effects must not re-fire. Send-side Idempotency-Key is a different header; you need both stories.
A timeout is not a carrier reject
Do not pause SMS because your CRM was slow. Isolate OTP devices so a webhook backlog cannot become a radio backlog.
Checklist
- HMAC verified first; secret not in the collection JSON.
- Handler p95 under your timeout with retries on.
- Idempotent on message/event id.
- No OTP bodies in webhook logs.
- TLS cert not expired.
- Canary event from a staff send.
Next steps
Fix the handler, then confirm a delivered SMS still matches one processed event. Setup · devices + volume.
Related product pages
Jump to the live product docs for this topic—not another long-form article.
- SMS webhook integrationInbound and status events
- SMS API documentationLive endpoint reference
- device and SMS volume pricingPlans and allowances
- Android SMS gateway product guideDefinition, product, and how to buy
