Key Takeaways
- Scenario 556 is 11:20 lunch-account low-balance failover — not exam dawn, homework, enrollment, snow-day, PTC, results, late-bus, field-trip, or after-school 17:10.
- A spare that IT racks at 09:00 and unplugs at 11:00 is not till HA.
- Priced by devices and SMS send volume. You use your own phone and operator SMS credit. Free is 300 SMS lifetime, 1 device. Developer is 25,000 SMS per year.
- Starter is 2 devices; the spare still counts.
- Hold PTA lists until the last low-balance notice drains.
- Canary both radios at 10:50, not at yesterday’s noon health check.
Summary
Scenario 556 is lunch-till failover. Low-balance notices leave Android SIMs you host before the 11:20 sitting.Service pricing is based on device count and total SMS sent through the gateway. You need a working Android phone with a SIM and SMS credit from your mobile operator. Operator message costs are yours—we do not sell carrier SMS balance.
If both phones live in a closet that locked at 11:00, lunch is not HA. It is a queue of pupils with a dead till.
Not a CodeCanyon “school SMS” pack. Device meters apply — Twilio vs Android SMS gateway.
Key takeaways
- Scenario 556 is 11:20 lunch-account low-balance failover — not exam dawn, homework, enrollment, snow-day, PTC, results, late-bus, field-trip, or after-school 17:10.
- A spare that IT racks at 09:00 and unplugs at 11:00 is not till HA.
- Priced by devices and SMS send volume. You use your own phone and operator SMS credit. Free is 300 SMS lifetime, 1 device. Developer is 25,000 SMS per year.
- Starter is 2 devices; the spare still counts.
- Hold PTA lists until the last low-balance notice drains.
- Canary both radios at 10:50, not at yesterday’s noon health check.
Related reading
multi-device and dual SIM routing, OTP and 2FA SMS, how an Android SMS gateway works, GOV.UK school meals.
Context
Parents top up from a phone at 11:15. PTA wants the same hour. One radio and a sleeping OEM policy will lose the sitting.
Free (300 SMS lifetime) is a rehearsal house. Developer is 25,000 SMS per year.
Core scenario guidance
Keep primary + spare paired through lunch. Health is last submit after 10:50, not a 09:00 screenshot.
Hold PTA until the last sitting. Locale per family if you span regions.
Lunch-till roles
| Role | When | Typical fail |
|---|---|---|
| Low-balance notice | 11:05–12:40 parent local | Phone in a locked office after 11:00 |
| Hot spare | Primary unpaired or submit errors | Unplugged when office closed for lunch |
| Parent portal OTP | Transactional, own pool | Dumped onto the till SIM |
| PTA / merch | Held until last sitting | Released at 11:10 into notices |
Cost and ownership
Priced by devices and SMS send volume. You use your own phone and operator SMS credit. The spare is a billed device. Resends burn airtime.
Name a 10:30–13:00 on-call for sittings, not only exam week.
Operations
10:50 canary both radios. Abort: hold PTA, keep till notices. Do not “resend all balances.”
Security and compliance
Minors: short bodies. No full balances in SMS if policy forbids. Authenticate till-app hooks. PTA is promotional.
Decision guide
Ship when 10:50 canary is green and the spare is reachable through lunch. Delay if phones lock at 11:00. If handsets are forbidden, CPaaS for parent OTP.
Checklist
- Primary + spare paired through lunch.
- 10:50 canary.
- PTA held.
- Portal OTP isolated.
- Per-parent resend limit.
- Airtime before 10:30.
- Battery exemptions both OEMs.
- Locale per family.
- Sitting on-call named.
- Device cap includes spare.
Next steps
Review device and SMS volume pricing, device setup, SMS API documentation.
Deep dive: production hardening
Cleaners pulling USB at 11:00 is an outage. Watch DLR, not SIS 200s.
Deep dive: scaling and failure modes
Multi-campus sittings add devices before inventing a hidden unlimited-handset SKU. Raise OEM ceilings; fair-use remains.
Deep dive: integration discipline
Idempotency on pupil_id + sitting_date + kind (low-balance). MCP is a REST wrapper — live fields in Developer Center.
Priced by devices and SMS send volume. You use your own phone and operator SMS credit.
10:50 till canary
Unplug primary. Confirm spare takes a staff notice. Hold PTA during the sitting.
Related product pages
Jump to the live product docs for this topic—not another long-form article.
- multi-device and dual SIM routingCapacity and failover
- OTP and 2FA SMS on AndroidAuthentication flows
- SMS delivery reports (DLR)Delivery status tracking
- SMS API documentationLive endpoint reference
