SMS alerts for DevOps teams.
A phone in a box.

Yes, within the bounded use case we target. Cellular carriers allow and expect "human-like" SMS traffic from consumer SIMs — the problem only arises when devices start looking like mass-marketing gateways (high volume, templated content, URL spam, low reply reciprocity). By hard-capping volume, blocking marketing keywords and URLs server-side, and handling STOP keywords automatically, we keep your traffic pattern firmly in the "technical alert" zone that carriers don't flag. If your use case is higher-volume or customer-facing, we'll route you to Twilio — we're not going to put your line at risk.

Automated health monitoring pings every device every 60 seconds. If your phone goes offline for more than 5 minutes, our system alerts us (and optionally you, via the webhook). For the Homelab and Team tiers, we ship a replacement within 1-2 business days. Production tier includes a hot spare — you just swap the SIM. In the meantime, our API returns 503 responses so your code can handle the outage gracefully.

Yes, if you have a nano-SIM from any carrier that supports SMS, you can pop it into the phone we ship. Works on T-Mobile, AT&T, Verizon, and all major MVNOs (Mint, US Mobile, etc.) in the US, and Freedom, Rogers, Bell, Telus in Canada. Physical nano-SIM only — the Samsung A5 2017 does not support eSIM.

We strongly recommend it — the phone joins your tailnet at provisioning time and is only reachable via Tailscale by default. That means zero public internet exposure. If you don't use Tailscale, we can also expose the API through our control plane at api.relaysms.dev, which bridges to your device over Tailscale on our side. You never need to open a port.

A refurbished Samsung Galaxy A5 (2017) running LineageOS 18.1 with microG, pre-installed with capcom6/android-sms-gateway (the open source HTTP SMS server, with our hardening fork), Tailscale, and a lightweight provisioning companion. Pre-debloated — no Google Play Services active, no Samsung bloatware, about 3 user apps total. Runs for years on a 5V wall adapter. Alternatives available for Production tier if you want newer hardware (Pixel 3a).

Absolutely — capcom6/android-sms-gateway is open source, LineageOS is open source, Tailscale is free. If you want to spend 8-12 hours of skilled engineer time flashing, configuring, hardening, and monitoring a phone yourself, go for it. We send you a pre-built version and handle support/replacements for $19/mo because most engineers' time is worth more than the maintenance. Your call.

The API returns 429 Too Many Requests with the quota reset time. The cap exists to keep you under carrier pattern-detection thresholds. If you regularly need more, we'll talk — either the Team/Production tier fits, or your use case has drifted toward "not our target audience" and we'll help you migrate to Twilio. We won't just silently raise the cap and let your number get flagged.

TCPA applies to unsolicited commercial messages to consumers. Our entire product is built to keep you firmly outside that category — internal team alerts and 2FA codes to your own employees are not within TCPA scope. Our TOS requires you to use the product only for internal or authenticated-recipient use cases, and we enforce that via content checks and abuse flags. If you need to message customers at all, this is not the right tool. Full TOS and acceptable use policy available at signup.

Canada: works great — Freedom Mobile, Rogers, Bell, Telus all supported. Europe: pending (different carrier environment, different regulations). APAC: not yet supported. US + Canada are the launch markets.

A solo engineer with a homelab obsession and enough DevOps experience to have hated Twilio's 10DLC process firsthand. This is a side project, deliberately run lean, deliberately scoped to the narrow niche where the approach actually works. If you want a Twilio-scale experience with global SMS coverage and 99.99% SLAs, this isn't it. If you want a simple phone-in-a-box that sends alerts for a flat fee, it is.