What is SMS Gateway for Android?

SMS Gateway for Android is an open-source app (Apache 2.0) that turns any Android phone running 5.0+ into a full SMS gateway with a REST API. You can send and receive SMS programmatically, get webhooks for incoming messages, and track delivery status — all without paying per-message fees to services like Twilio.

How much does SMS Gateway for Android cost compared to Twilio?

The software is free and open-source. Your only cost is the SIM card and carrier plan. Twilio charges $0.0079 per outbound SMS in the US. A startup sending 10,000 messages/month pays ~$79/month on Twilio vs. a flat carrier plan (~$15-25/month) with this gateway.

Is SMS Gateway for Android secure?

Yes. It supports end-to-end encryption — message content and phone numbers are encrypted before leaving the device. You can also run a private backend server in your own infrastructure instead of using the cloud relay.

Can I use multiple phones with SMS Gateway?

Yes. Multi-device support lets you connect multiple phones to the same account. Messages sent via the server are distributed across all connected devices. Each phone can also have multiple SIM cards for even more capacity.

What are the limitations of using this instead of Twilio?

Carrier-level limitations apply: mobile operators may flag or throttle high-volume sending from consumer SIM cards. It's not recommended for batch/bulk marketing SMS. It's ideal for transactional messages — 2FA codes, order confirmations, appointment reminders, and notifications at moderate volumes.

Does it work without internet or a cloud server?

Yes. In local mode, the API runs directly on the device with no cloud server or registration required. You connect to the phone's local IP on your network. Cloud mode is optional for when the device isn't on the same network.

SMS Gateway for Android: Turn Any Old Phone Into a Free Twilio Replacement

By Prahlad Menon Published 2026-04-06 5 min read

Twilio charges $0.0079 per SMS. That adds up fast — startups routinely spend $500 to $5,000/month on SMS APIs for authentication codes, order confirmations, and notifications.

SMS Gateway for Android eliminates that line item entirely. Install it on any Android phone. Insert a SIM card. You now have a full SMS sending and receiving server with a REST API.

No registration. No per-message pricing. No contracts.

What It Actually Does

The app turns an Android phone into an API-accessible SMS gateway. Your backend sends an HTTP request to the phone, the phone sends the SMS through its SIM card, and you get a delivery status callback.

The core workflow:

Install the APK on any Android 5.0+ phone
The phone runs a local HTTP server
Your app calls the REST API to send messages
Incoming messages trigger webhooks to your server
Delivery status updates flow back in real time

That’s it. The phone is the infrastructure.

Key Features

No account required in local mode. The API runs directly on the device. Connect to it on your local network. No cloud dependency, no email signup, nothing.

End-to-end encryption. Message content and recipient phone numbers are encrypted before they leave the device. If you use the optional cloud relay, the cloud server never sees plaintext.

Multi-SIM support. Dual-SIM phones let you use both SIMs. Choose which SIM sends which messages via the API.

Multi-device support. Connect multiple phones to the same account. Messages are automatically distributed across devices — primitive but effective load balancing.

Webhooks for incoming messages. Get notified instantly when an SMS, Data SMS, or MMS arrives. Process inbound messages in your own backend.

Multipart auto-splitting. Long messages are automatically split and reassembled. You send the full text; the gateway handles the 160-character segmentation.

Delivery tracking. Monitor the status of every message in real time — sent, delivered, failed.

Private server option. Don’t want to use the cloud relay at all? Run the backend server on your own infrastructure for complete control.

The API

Sending an SMS is a single POST request:

curl -X POST http://PHONE_IP:8080/api/v1/message \
  -H "Content-Type: application/json" \
  -d '{
    "phoneNumbers": ["+1234567890"],
    "message": "Your verification code is 847291"
  }'

The response includes a message ID for tracking delivery status. Webhooks fire on status changes.

Cost Comparison

	Twilio	MessageBird	SMS Gateway
Per SMS (US)	$0.0079	$0.0068	$0
Monthly platform fee	$0	$0	$0
Phone number rental	$1.15/mo	$1.00/mo	Your SIM
1,000 msgs/month	~$9	~$8	~$0 (carrier plan)
10,000 msgs/month	~$80	~$69	~$0 (carrier plan)
100,000 msgs/month	~$790	~$680	Not recommended
Setup	API key	API key	Install APK
Reliability	99.95% SLA	99.95% SLA	Depends on phone/carrier
Bulk sending	✅ Designed for it	✅ Designed for it	⚠️ Carrier may throttle

The sweet spot: Under ~10,000 messages/month for transactional use cases. Above that, carriers start noticing and you risk throttling or account flags.

What It’s Good For

Two-factor authentication — Send verification codes from your own infrastructure
Order confirmations — E-commerce notifications without per-message costs
Appointment reminders — Healthcare, salons, services
Alert notifications — Server monitoring, IoT alerts, security notifications
Internal tools — Team notifications, on-call alerts
Development/testing — Stop burning Twilio credits during development

What It’s Not Good For

Bulk marketing — Carriers will flag you. Use a real SMS aggregator.
High-volume transactional — Above 10K/month, you need proper short codes or toll-free numbers
Mission-critical uptime — Your phone crashes, your SMS gateway goes down. Twilio has redundancy; an old Pixel in your drawer does not.
International sending — Carrier rates for international SMS vary wildly. Twilio’s pricing is predictable.

The “Old Phone in Your Drawer” Play

This is the real insight. That Android phone you upgraded from two years ago? It’s sitting in a drawer doing nothing. Put a $15/month prepaid SIM in it, install this app, and you have a private SMS server.

For a startup in the early stages — sending a few hundred auth codes and order confirmations per month — this is genuinely free infrastructure that replaces a $50-100/month Twilio bill.

Setup

Download the APK from GitHub releases
Install on any Android 5.0+ device
Grant SMS permissions when prompted
The app shows your local API endpoint
Start sending via the REST API

For remote access (device not on same network), you can use the optional cloud server or set up your own private server instance.

Full API docs: docs.sms-gate.app

The Numbers

3,424 GitHub stars
588 forks
359 commits
Apache 2.0 license
Active development since 2022
Kotlin + Ktor + Room under the hood

Android AI Agents: What’s Actually Possible — More ways to turn Android phones into infrastructure
CLI-Anything: Making All Software Agent-Native — The broader trend of API-ifying everything