Key Takeaways
- Tenant isolation on an Android SMS gateway is API keys, device pools, and log access — not a CSS theme on a shared modem.
- Start from the server cornerstone. This spoke is the split, not a reseller playbook.
- One SIM sending two customers’ OTP is a confidentiality bug even if HTTP 200 looks fine.
- Contracted branding does not create a turnkey multi-tenant SMS business. Device and volume meters still apply.
- You bring each tenant’s phones and operator credit unless the contract says otherwise. We meter devices and send volume.
Isolation is keys and radios
Cornerstone: Android SMS gateway server. This spoke is tenant isolation basics: who can send as whom, which phone claims the job, and who can read the inbox. SMS Retriever / OTP hashes still assume the sender number is the one the app expected.
We meter devices and volume per account. Sharing one Free-tier phone across “tenants” is not a product. Do not title this “Unlimited SMS.”
What must not mix
Live auth is Bearer keys. Live send fields: Developer Center. Do not invent a tenantId header unless that document lists it. Your adapter can map customers to keys and deviceIds you already own.
“Isolation is keys and devices, not a CSS theme on a shared modem.”
Shared vs isolated
| Surface | If shared | Isolated design |
|---|---|---|
| API keys | One leak is every customer | Per tenant (or per env) keys; rotate independently |
| Devices / SIMs | Wrong From; mixed STOP; mixed airtime | Named pools; OTP phones never run another tenant’s CSV |
| Inbound inbox | Replies land in the wrong CRM | Webhook URLs and routing per tenant |
| Logs / exports | MSISDNs leak across support desks | Access control and retention per account |
| Airtime | One load card funds rival traffic | Each SIM’s operator bill is that tenant’s |
OTP and logs
Login codes are high-sensitivity. Isolate OTP devices even inside one company. Retention of message bodies is a privacy choice — treat it like production PII. Baseline: OWASP ASVS.
Branding is not tenancy
Custom panel branding is contracted, starting from a setup fee, and still sits on device + volume plans. It is not a license to resell carrier SMS. Scope: talk to sales.
Next steps
Draw tenants as keys × device names × webhook URLs. Canary that a key cannot see another inbox. Plans: pricing. Operator credit stays with whoever owns the SIM.
Related product pages
Jump to the live product docs for this topic—not another long-form article.
- device and SMS volume pricingPlans and allowances
- Android SMS gateway product guideDefinition, product, and how to buy
- SMS API documentationLive endpoint reference
- download the Android gateway appGet the APK
