Does a dunning webhook include carrier credit?

No. Priced by devices and SMS send volume. You use your own phone and operator SMS credit. A replayed payment_failed still costs airtime if you send again.

Should payment_failed use the same SMS as cart.abandoned?

No. Dunning is a billing notice with a documented retry cap. Cart is promo with STOP. Mixing them is how you coupon a failed charge.

Can checkout OTP share the renewal-dunning phone?

No. Isolate OTP from subscription traffic so a billing-day queue cannot starve authentication.

Android SMS Gateway Scenario 157: Ecommerce webhooks in practice

Key Takeaways

invoice.payment_failed is dunning: HMAC, invoice id, one retry ladder — not an abandon-cart coupon.
subscription.renewed is a receipt; it must not reuse the failed-charge template.
Checkout OTP stays off the dunning SIM so a billing-day wave cannot starve login codes.
Priced by devices and SMS send volume. You use your own phone and operator SMS credit. Processor retries still meter platform volume and carrier airtime.
Free is 300 SMS lifetime on one device — canary one failed invoice, not a full renewal day.
Developer Center owns live API parameters; billing owns the retry ladder.

Summary

Billing day is not a cart campaign. invoice.payment_failed needs HMAC, an invoice id, and a short retry ladder. It must never reuse abandon-cart copy or the checkout OTP radio. Priced by devices and SMS send volume. You use your own phone and operator SMS credit.

If the processor retried the charge, your invoice id is the only thing standing between you and a second dunning text.

Renewal fail vs cart promo

Topic	SMS type	Skip when
invoice.payment_failed	Dunning, capped retries	HMAC fail or same invoice already sent
subscription.renewed	Receipt, once	Duplicate period id
cart.abandoned	Promo + STOP	Never on the dunning SIM
checkout OTP	Auth only	Any billing phone

Key takeaways

payment_failed is dunning, not a coupon.
Renewed is a receipt with its own idempotency key.
Checkout OTP stays off the dunning SIM.
Priced by devices and SMS send volume. You use your own phone and operator SMS credit.
Developer Center owns live API parameters.
Canary one failed invoice on staff before billing day.

Context

Billing engineers use this ecommerce scenario to fire dunning SMS only after HMAC and invoice-id checks say the failed charge is new.

Radio reality still wins: offline phones and OEM killers break scenarios overnight.

Cross-link hub cornerstones instead of rewriting the product overview.

Keep examples conceptual until Developer Center confirms live request shapes.

Budget airtime for retries — failed loops still cost operator credit.

Core scenario guidance

Map payment_failed, renewed, and checkout-OTP to separate templates and radios before you subscribe billing topics.

Separate configuration mistakes from radio failures during incidents.

Write acceptance criteria before seasonal or clinic-hour traffic.

Prefer gradual rollout with feature flags when automation is involved.

Cost and ownership

Model billing day as devices plus volume plus airtime on every un-deduped processor retry. Free is 300 lifetime SMS for one staff invoice.

Failed retries still burn credit during scenario experiments.

Assign who owns SIM top-ups and spare handsets.

Keep marketing spend out of OTP device pools.

Operations

Daily checks: pairing health, battery, queue depth, and DLR anomalies.

After OEM updates or SIM swaps, re-test the scenario path end to end.

Keep a spare charged device ready for failover drills.

Name an on-call owner before unattended sends go live.

Security and compliance

Protect API keys per environment; rotate after contractor access ends.

STOP and consent still apply on promotional scenario lanes.

Avoid logging full OTP bodies into shared chat.

Verify webhook signatures and TLS on every callback path.

Decision guide

Ship renewal dunning only when HMAC, invoice idempotency, and OTP isolation are written.

Delay if you cannot explain offline-phone behavior during peak hours.

If zero phone ops is mandatory, evaluate CPaaS for that lane.

If local SIM economics matter, harden the Android path and monitor airtime.

Checklist

Scenario moments listed with owners.
OTP vs marketing isolation confirmed.
Spare device funded and paired.
Canary on staff numbers passed.
Developer Center checked if API-shaped.
Webhook/DLR monitoring ready.
Airtime budget includes retries.
On-call owner named.
Rollback path documented.
Hub cornerstone reviewed.

Next steps

Return to API guide, compare device and SMS volume pricing, open device setup guide, and confirm APIs in SMS API documentation.

Deep dive: production hardening

Appointment businesses live on reminder deliverability the morning of the visit.

Bulk CSV import needs validation before radio send; bad rows burn airtime.

Scheduled SMS must survive device sleep and timezone mistakes.

Auto-reply and STOP protect promotional lanes — never auto-reply into OTP threads.

Dual SIM routing fails when slot maps drift after reboot without re-pair.

Multi-device failover only helps if spare phones stay charged and paired.

MMS attachments inherit carrier size and APN limits.

USSD requests are carrier- and region-sensitive; treat timeouts as expected.

Contact lists need consent metadata stored with the number.

OTP priority queues fail when marketing blasts share the same device pool.

Spare charged devices matter more than brochure SLAs when phones send the SMS.

Airtime surprise bills happen when bulk loops ignore radio pace.

OTP and marketing must stay on separate lanes on every scenario.

Never claim unlimited free cloud SMS credits with no device or volume meter.

Name an on-call owner before unattended schedules go live.

Canary on staff numbers before customer OTP.

Battery exemptions and OEM killers dominate overnight reliability.

Cross-link Setup, Pricing, Downloads, and Developer Center with keyword-rich anchors.

If zero phone ops is mandatory, evaluate CPaaS for that lane instead.

Webhook signature verification is non-negotiable for scenario automation.

Document who owns SIM top-ups for multi-site scenario rollouts.

Prefer honest latency expectations over marketing claims about global SLAs on SIM paths.

Scenario playbooks still bill by devices and SMS send volume. You bring the Android phone and operator SMS credit.

Developer Center owns live API parameters. Scenario blogs teach process and failure modes, not endpoint catalogs.

Ecommerce webhooks must verify signatures before they trigger SMS sends.

Clinic reminders need consent records and STOP handling even when messages feel transactional.

Logistics ETAs should degrade gracefully when devices go offline mid-route.

Edtech OTP spikes at exam windows — capacity plan devices before the semester starts.

Fintech OTP is high-stakes: isolate devices, rotate keys, and avoid logging full codes.

Real-estate nurture is promotional; keep it off OTP SIMs and honor quiet hours.

Restaurant reservation SMS still needs STOP on marketing lanes.

SaaS onboarding OTPs should canary on staff numbers before paid scale.

Field-service dispatch needs two-way inbox ownership so techs are not double-booked.

Marketplace seller alerts need multi-device failover when a single phone is the SPOF.

NGO outreach must separate fundraising blasts from operational alerts.