Android SMS Gateway Scenario 176: SaaS onboarding two-way inbox in practice

Summary

Scenario 176 is workspace seat invites over a two-way Android inbox. YES provisions. HELP is a person. SSO OTP is a different radio. 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 a teammate’s YES retries three times and you bill three seats, you do not have onboarding SMS. You have a billing incident with a SIM attached.

The FROM is your handset — Twilio vs Android SMS gateway.

Key takeaways

• Scenario 176 is teammate-invite SMS: YES joins a seat, HELP needs a human, SSO OTP lives elsewhere.
• A YES without idempotent invite_id double-provisions seats and bills the admin.
• Priced by devices and SMS send volume. You use your own phone and operator SMS credit. Free is 300 SMS lifetime, 1 device.
• STOP on invite follow-ups. SSO codes must not share this MSISDN.
• Workspace-admin locale owns the HELP SLA, not HQ Pacific by default.
• Every CSM reply spends airtime and platform volume.

Related reading

two-way SMS inbox, SMS auto-reply and STOP keywords, OTP and 2FA SMS, FCC unwanted-text guidance.

Context

Admins invite teammates by mobile. Product wanted activation. Finance wanted seat counts. Security wanted SSO codes isolated. One drawer phone cannot do all three.

Free (300 SMS lifetime, 300 contacts) is a staff rehearsal.

Core scenario guidance

Idempotent invite_id on YES. Auto-ack HELP. Honor STOP with no “but your admin invited you” paragraph.

Map inbound to the last outbound invite. Orphans get search, not a second seat.

Invite inbound owners

Cost and ownership

Priced by devices and SMS send volume. You use your own phone and operator SMS credit. Reminders and CSM replies are sends. Budget airtime for conversations.

Name who watches HELP during the admin’s workday.

Operations

Daily: oldest HELP, double-provision alerts, SSO OTP canary on the other phone.

Abort: pause invite drips, keep SSO OTP, empty HELP.

Security and compliance

No session tokens in SMS. Rotate keys after a growth contractor. Verify inbound webhooks before they add seats.

Invite follow-ups are promotional enough for STOP. SSO is not a drip.

Decision guide

Ship when YES is idempotent and SSO is isolated. Delay if inbound is “we’ll check Monday.” If you refuse handsets, CPaaS for OTP and email for seats.

Checklist

• SSO OTP isolated.
• YES keyed by invite_id.
• STOP instant.
• HELP human SLA.
• Webhook HMAC.
• Airtime includes replies.
• Staff canary of YES + HELP.
• On-call for seat-wave weeks.
• Double-seat alert.
• Developer Center for receive payloads.

Next steps

Use two-way SMS, device and SMS volume pricing, SMS API documentation.

Deep dive: production hardening

OEM sleep kills inbound. Charge and exempt the inbox phone.

Dual-SIM remap: SSO codes must not hop onto the invite number.

Do not auto-reply a drip into STOP.

Pace invite waves. OEM ceilings and fair-use still apply.

Deep dive: scaling and failure modes

More seats means more replies. Devices still meter. No unlimited-SMS title.

Multi-region workspaces need HELP hours per admin locale.

Outage + SSO surge: hold invite drips.

Deep dive: integration discipline

Idempotency on invite_id. Widget retries are the default.

Feature-flag invite copy. Canary one workspace before a 2,000-seat rollout.

Priced by devices and SMS send volume. You use your own phone and operator SMS credit. Live fields stay in Developer Center.

Seat-invite drill

Staff YES twice; confirm one seat. HELP routes. STOP suppresses follow-up only.

SSO OTP latency must not move during an invite wave.

Abort: pause drips, keep SSO, empty HELP. If growth can override, you do not have a desk.