Key Takeaways
- Prepaid vs postpaid on a gateway server is still an operator tariff. Cloud relay and local mode do not vend airtime.
- Empty prepaid looks like device unhealth (Pending, failed DLR). Unpaid postpaid looks like a surprise bar after a bill.
- Hub F cornerstone is the server guide. API-hub tariff how-to is a sibling — this page is what on-call sees.
- OTP wants a plan that survives 02:00 without a voucher hunt. Campaigns can sit on prepaid with alerts.
- Platform pricing is devices plus send volume. You bring phones and carrier credit. Starter, Professional, and Business list Unlimited SMS as platform send volume; that is not unmetered carrier SMS.
Tariff is not the control plane
Cornerstone: Android SMS gateway server. API-hub sibling: prepaid vs postpaid (API). Device health: device health checklist.
We meter devices and volume. Load is the operator. Starter, Professional, and Business list Unlimited SMS as platform send volume; that is not unmetered carrier SMS.
How empty SIMs look on the server
Last-seen can stay green on data while SMS fails closed (prepaid zero) or after a bar (postpaid unpaid). On-call should USSD before rewriting firewall rules. Live API: Developer Center.
“A local-mode server with a dead voucher is still a dead radio. The rack did not buy airtime.”
Prepaid vs postpaid for gateway servers
| Prepaid | Postpaid | |
|---|---|---|
| Empty / barred | Fails closed; USSD zero | May send, then bar on invoice |
| On-call 02:00 | Needs auto top-up + spare | Usually keeps sending to credit limit |
| Dashboard lie | Paired, Pending forever | Paired, then sudden fail spike |
| Finance | Voucher wallet | Monthly bill; watch volume |
| Who pays SMS | You → operator | You → operator — not the gateway SKU |
OTP vs campaign SIMs
Pin login to postpaid or auto-top-up prepaid. OTP. Campaigns: bulk CSV. Setup: pairing.
Local mode changes nothing
DIY TLS does not include pulsa. Fair-use still applies. GSMA. Pricing.
Next steps
Label each rack SIM prepaid/postpaid and name the top-up owner. Canary after a planned zero-balance drill on a spare only. Operator credit stays yours.
Related product pages
Jump to the live product docs for this topic—not another long-form article.
- SMS API documentationLive endpoint reference
- device and SMS volume pricingPlans and allowances
- Twilio vs Android SMS gatewayCloud vs own-SIM cost model
- Android SMS gateway product guideDefinition, product, and how to buy
