Key Takeaways
- Monthly operator cost on a core Android SMS gateway is (sends + retries) × parts × the SIM tariff — not the gateway plan price.
- The service fee is devices plus platform send volume. Airtime is a second ledger you already pay the carrier.
- Hub A product walkthrough stays on how the gateway works. This how-to is the finance worksheet at core-product scope.
- UCS-2 and failed OTP loops are the usual under-budget. GSM-7 OTP digits stay cheaper.
- Free is 300 SMS lifetime on the platform. Developer is 25,000 SMS per year. Neither is operator credit.
Two ledgers
Product: how an Android SMS gateway works. Deeper app-hub worksheet: estimate monthly operator cost (app). This Hub A how-to is the short model: carrier vs platform.
Pricing is devices + send volume. You fund the SIM. Starter, Professional, and Business list Unlimited SMS as platform send volume; that is not unmetered carrier SMS.
Operator-cost formula
Monthly airtime ≈ attempts × parts per attempt × tariff per part. Attempts include retries. Parts jump when copy leaves GSM-7. Live send fields: Developer Center— no invented cost key.
“If finance only sees the Stripe line, they have not priced SMS. They have priced the control plane.”
What belongs on which bill
| Line | Who bills | Notes |
|---|---|---|
| Device + platform volume | SMS Gateway | Free 300 lifetime; Developer 25k/year |
| SMS parts | Mobile operator | Prepaid load or postpaid invoice |
| Retries / concatenations | Operator | OTP loops and Unicode |
| Phones, UPS, SIMs | You | Capex / opex, not a message fee |
| Failed DLR resends | Operator again | Cap them; see DLR |
Parts and retries
ASCII OTP wrappers stay one part more often. Marketing with emoji does not. Isolate OTP so a campaign cannot multiply login retries. Prepaid vs postpaid: tariff choice.
Where the gateway fee sits
Add device count × plan, then airtime. Industry context: GSMA. Setup: pairing.
Next steps
Pull last month’s accepted + retry counts. Multiply by your part rate. Name who tops up. 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
- Android SMS gateway product guideDefinition, product, and how to buy
- download the Android gateway appGet the APK
