Key Takeaways
- Invoice-correction webhooks are amount delta and last-four — never a full tax ID in SMS.
- Verify signatures before the SIM fires. A replayed invoice.corrected is a second “your bill changed” text.
- Keep checkout OTP off the finance tablet that dumps correction bursts.
- Service pricing is devices plus SMS send volume. You bring the Android phone and operator credit.
- Free is 1 device, 300 SMS lifetime, 300 contacts. Developer is 25,000 SMS per year.
- Idempotency on correction id, not on “invoice + today.”
Summary
Ecommerce webhooks in scenario 949 are invoice corrected: amount delta, last-four, portal. Unlike order.paid, restock, refund, subscription, gift-card, BOPIS, split-shipment, RMA labels, COD, preorder drop, price-match credit, remaining-line ships, warranty registration, loyalty expiry, or backorder available, this event is finance fixing tax on a posted invoice.
Service pricing is devices plus SMS send volume. You bring the Android phone and operator SMS credit. Free is 1 device, 300 SMS lifetime, 300 contacts. Developer is 25,000 SMS per year. Starter, Professional, and Business list Unlimited SMS as platform send volume; devices and airtime stay metered.
A VAT number in SMS is a company identifier you leaked. Verify the webhook. Send delta and last-four. Keep the tax ID on the PDF.
Key takeaways
- Invoice-correction webhooks are amount delta and last-four — never a full tax ID in SMS.
- Verify signatures before the SIM fires. A replayed invoice.corrected is a second “your bill changed” text.
- Keep checkout OTP off the finance tablet that dumps correction bursts.
- Service pricing is devices plus SMS send volume. You bring the Android phone and operator credit.
- Free is 1 device, 300 SMS lifetime, 300 contacts. Developer is 25,000 SMS per year.
- Idempotency on correction id, not on “invoice + today.”
Related reading
Start from Twilio vs Android SMS gateway, compare device and SMS volume pricing, open device setup, and review OECD invoice notes where they apply.
Context
Finance desks land here after a replayed invoice.corrected texted twice, or after a tax ID leaked in the body. Checkout OTP cannot share that burst.
Core scenario guidance
Verify signatures. Idempotency on correction id. Template: delta, last-four. Tax ID on PDF. Isolate OTP. Cap retries.
| Event | SMS body | Fail closed |
|---|---|---|
| invoice.corrected | Delta + last-four | VAT / GST number |
| invoice.voided | Portal reason | Full invoice PDF in SMS |
| Idempotency | Correction id | Invoice + today |
| Checkout OTP | Separate device | Same SIM as finance burst |
Canary a staff correction after OS updates. MCP wraps REST. Developer Center owns fields.
Cost and ownership
Devices + volume + operator airtime on every replay. Developer is 25,000 SMS per year. Free (1 / 300 / 300) proves pairing, not a finance desk.
Operations
Daily last-seen, battery, webhook fail, duplicate correction ids. After SIM reseat, one staff delta. On-call before unattended close weekends.
Security and compliance
Correction events reveal tax IDs. Encrypt at rest. Rotate webhook secrets. Never log VAT numbers. Verify TLS on every callback.
Decision guide
Ship when signatures, correction-id idempotency, and tax-ID isolation exist. Delay if finance can replay corrected. If zero phone ops is mandatory, evaluate CPaaS for that slice.
Checklist
- Webhook signatures verified.
- Correction id idempotent.
- No tax ID in SMS.
- OTP isolated.
- Spare paired.
Next steps
Return to App guide, compare device and SMS volume pricing, open device setup, and confirm APIs in SMS API documentation.
Deep dive: production hardening
Webhook signature verification is non-negotiable. Dual-SIM finance tablets fail when the send slot swaps after reboot. Battery exemptions dominate overnight close.
Deep dive: scaling and failure modes
Scale is invoices times corrections, not a blast of the catalog. Never claim unlimited free cloud SMS credits with no device or volume meter.
Deep dive: integration discipline
Developer Center owns live API parameters. Persist correction id. MCP is a REST wrapper. If zero phone ops is mandatory, evaluate CPaaS. You bring the Android phone and operator credit.
Related product pages
Jump to the live product docs for this topic—not another long-form article.
- SMS webhook integrationInbound and status events
- transactional SMS for orders and alertsEvent-driven messages
- SMS API documentationLive endpoint reference
- device and SMS volume pricingPlans and allowances
