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SMS

How to Send SMS with Bitcoin Lightning

Send a text message to any phone number in 200+ countries directly from your browser. No SIM card, no carrier plan, no account. Pay with Lightning — from 5 sats per message.

Varies by destinationNo account required200+ countriesL402 / MCP / OpenClaw

For Humans

Use cases for individuals and travelers

Text international numbers while traveling

Your carrier charges $0.50 per international SMS — or blocks it outright. Send from your browser on hotel WiFi for a few sats. No roaming plan, no add-on package, no SIM swap needed.

Text without a phone

At a computer and need to reach someone by text right now. Open the page, type the message, scan the QR. No app to install, no account to create, no phone in your hand required.

Messages not tied to your number

Messages are sent from a service number, not your personal phone. No account means no email, name, or identity linked to the message. Pay with Lightning and leave no trail beyond the delivery.

Text anyone globally with just Bitcoin

Many people worldwide have Bitcoin but no international carrier plan or credit card. Lightning opens texting to anyone with sats — from any country, to any country, with no financial infrastructure required beyond a wallet.

SMS to Mobile Numbers

Global SMS via Lightning

Varies by country
price shown before payment
200+ countries
US, UK, EU, Asia, LatAm...
No account
No email, no sign-up
Any browser
No app needed
L402 / MCP
Fully automatable

How It Works

1

Enter phone number and message

Go to sats4ai.com/sms. Enter the destination number with country code (+1 for US, +44 for UK, etc.) and type your message.

2

See the price

The exact cost for your destination is shown before you commit — no hidden fees. Prices vary by destination country — the exact cost is shown before you pay.

3

Pay the Lightning invoice

Click Send. A QR code appears for the exact price. Scan with any Lightning wallet — Phoenix, Breez, Wallet of Satoshi, or a WebLN browser wallet.

4

Message delivered

Your SMS is delivered immediately after payment confirms. The recipient receives a standard text message — no app required on their end.

For Agents

Use cases for AI agents, automation pipelines, and developers

No API key needed. The SMS endpoint uses L402 — pay-per-message via Lightning. Agents send a phone number and message body, receive a 402 with an invoice, pay it, and the SMS is delivered. No contracts, no number provisioning, no monthly minimums.

Alerts and monitoring

Fire off an SMS when a server goes down, a pipeline fails, or a threshold is breached. No telecom account setup — just an L402 call that costs a few sats per alert. Cheaper and simpler than maintaining a carrier API contract for low-volume alerting.

AI-generated notifications

Chain AI Chat with SMS: generate a personalized message using an LLM, then text it directly to the recipient. Automated summaries, AI-drafted updates, or response dispatching — all paid per message in sats.

Verification and OTP delivery

Send one-time passwords or confirmation codes to users without signing up for a telecom provider. Pay per message — scale from one code to thousands without tier negotiations or monthly minimums.

Multi-channel outreach pipelines

Build agents that send a text first, then follow up with a phone call if no response. Or chain transcription → AI Chat → SMS to automatically process voicemails and send written summaries. All services pay-per-use via the same Lightning flow.

L402 Authentication Flow

1
Send the request without auth — POST the phone number and message to the endpoint. The server responds with HTTP 402 and a Lightning invoice.
2
Pay the invoice — The agent pays the Lightning invoice using a connected wallet. Confirms in milliseconds.
3
Resend with payment proof — Resend the request with the payment preimage in the Authorization header. The SMS is delivered.
terminal
# Step 1: Send request (returns 402 + invoice)
curl -X POST https://sats4ai.com/api/l402/send-sms \
  -H "Content-Type: application/json" \
  -d '{"phone_number": "+14155550100", "message": "Your order has shipped."}'

# Step 2: Pay the Lightning invoice

# Step 3: Resend with payment proof
curl -X POST https://sats4ai.com/api/l402/send-sms \
  -H "Content-Type: application/json" \
  -H "Authorization: L402 <token>:<preimage>" \
  -d '{"phone_number": "+14155550100", "message": "Your order has shipped."}'

MCP & OpenClaw

MCP Server

Connect Claude, Cursor, or any MCP-compatible agent. The agent calls send_sms as a tool — Lightning payment handled automatically.

OpenClaw

One-line MCP setup. No API key required — agents authenticate with Lightning payments automatically on every call.

Chain with Other Services

AI Chat
SMS

Generate a personalized message with an LLM, then text it directly to a phone number. AI-drafted notifications, summaries, or responses — delivered as a standard SMS.

SMS
Phone Call

Text first, then follow up with a call if no response. Multi-channel outreach with no telecom contracts on either channel.

Transcription
AI Chat
SMS

Transcribe a voicemail, summarize it with AI Chat, and send the summary as a text to the recipient. Automated voicemail-to-text pipeline.

TTS
Phone Call
SMS

Generate a voice message, deliver it via call, then send a written follow-up SMS. Voice-first outreach with text backup.

Send SMS — No Signup Required

Price varies by destination. 200+ countries. All you need is a Lightning wallet. No SIM card, no carrier plan, no account.

Send SMSL402 API & MCP Docs