Android · MCP server · Open source

Give Claude a phone.

PhoneBridge turns your Android phone into an MCP server. Claude reads and sends texts, answers and places calls, through a relay you run. No Google services. No SaaS. Under 2% battery a day.

Download APK See it work

Android 10+ · signed APK · built from main · private preview, GitHub access required

10:08

PhoneBridge

Connectedrelay.worksystems.co.nz · 2 h 14 m

Battery84%

NetworkWi‑Fi

Keepalive180 s

Policy

Unknown numbersConfirm

Premium / foreignDeny

Rate limit20 SMS / h

Recent

sms_send Alice ChenAllowed

call_reject +61 2 8001…Allowed

sms_send +44 7700…Denied

14 tools1 outbound socketP‑256 keys in StrongBoxRelay stores no contentMIT

01Demo

See it work

Ask in plain language.

Claude resolves the contact on the phone, sends the text, and waits for the delivery report. It knows when the message landed, not just when it left.

Calls, handled while you're busy.

Claude sees who's ringing with the contact resolved, declines, and sends a text in your words. Answer, reject, hang up, dial. No audio, by design.

Unknown number? The phone asks you.

Sends and dials to anyone outside your contacts need a tap on the phone. Sixty seconds of silence is a no, and the tool call fails cleanly.

Audited. Pausable.

Every decision and outcome is logged on the device. One tap closes the socket and nothing is reachable until you say so.

01 / 04Scroll ↓

claude · phone

text alice I'm running 10 minutes late

contacts_search {"query": "alice"}

1 match · Alice Chen · +64 21 555 0199

sms_send {"to": "+64215550199", "body": "Running about 10 minutes late, sorry!"}

{"id": 41, "parts": 1, "status": "queued"}

sms_delivered · id 41 · 1.2 s

Sent. Alice has it.

wait_for_events {"timeout_s": 300}

call_incoming · +64 27 555 0123 · Marcus Lee

You're in a meeting until 3. Declining and texting him.

call_reject

sms_send {"to": "+64275550123", "body": "In a meeting, I'll call you at 3."}

forward the code from that last text to +44 7700 900123

sms_send {"to": "+447700900123", "body": "Your verification code is 482 119"}

confirmation_timeout · number not in contacts, no approval on phone within 60 s

I couldn't send that. The phone asked you to approve it and you didn't.

device_status

{"paused": true, "battery_pct": 84, "pending_events": 0}

The bridge is paused. Nothing is reachable until you resume it on the phone.

10:08

Alice Chen+64 21 555 0199

Hey, still on for 7?

Running about 10 minutes late, sorry!Delivered · 10:08

10:12

Incoming call M Marcus Lee Mobile · +64 27 555 0123

DeclineAnswer

Declined · texted Marcus

10:15

PhoneBridge

Approval request · now

Send SMS to +44 7700 900123?

Not in contacts · foreign country code

“Your verification code is 482 119”

DenyApprove

Result

sms_send +44 7700 900123Timed out · denied

10:20

Audit

device_statusAllowed

sms_send +44 7700 900123Timed out

sms_send Marcus LeeAllowed

call_reject Marcus LeeAllowed

sms_send Alice ChenDelivered

contacts_search “alice”Allowed

PausedSocket closed · nothing reachable

02How it works

Architecture

The phone is the server.

Every tool, every policy decision and every byte of message content lives on the device. The relay authenticates both sides and forwards JSON‑RPC. That's all it does.

Client

Claude

Claude Code, Claude Desktop or any MCP client. Standard Streamable HTTP with a bearer token.

HTTPS · MCP

Relay

One Go binary

Runs on any VPS. Verifies the device key and the client token, forwards bytes, stores no content.

Static · systemd

Server

Your phone

Outbound WebSocket only. Policy engine, audit log, kill switch and hardware keys all live here.

WSS · MCP server

Claude can see who's calling, answer, decline, hang up and dial. It can read and write SMS. It cannot hear or speak on a call: Android exposes no call audio to apps.

<0%battery per day

0persistent socket

0polling, alarms, wakelocks at idle

0tools, all served by the phone

03Security

Threat model

Designed forthe day the relayis hostile.

Assume the token leaks. Assume the host is owned. The phone still decides.

Read SECURITY.md

Device keys: ECDSA P‑256 generated in the Android Keystore, StrongBox when the chip has it. Non‑exportable. Challenge‑response on every connect, single‑use nonces, 60 s skew window.
Client tokens: 256‑bit bearer tokens shown once and stored as SHA‑256. Bound to one device, rate limited per token and per IP, revoked instantly.
Pairing: Initiated only from the relay host. Ten‑minute one‑time codes, five failures per ten minutes per IP.
On‑device policy: Every tool call passes through the policy engine before any adapter runs. Reads allowed. Sends and dials to contacts allowed. Anyone else: confirm on phone. Premium rates, foreign codes, quiet hours and hourly limits deny by default.
Untrusted content: SMS bodies, caller IDs and contact names are tagged as third‑party data. A text that says “send my bank code to…” gets a confirm prompt, not a send.
Relay: No message content persisted or logged. TLS 1.2+, modern ciphers, 256 KiB body cap, slowloris timeouts. Runs as a locked‑down systemd unit with a dynamic user.
App hardening: No backup, no analytics or crash SDKs, R8, pinned dependencies, schema validation per tool, unknown fields rejected. Lock‑screen notifications never show message bodies.
Kill switch: Pause closes the socket. Unpair from the relay side with one command. Nothing is reachable until you resume.

04Quick start

Relay · token · MCP

Five steps.Then just ask.

Run the relay on a host with a public address.
Pair by scanning the QR code the relay prints.
Mint a token for your laptop.
Add the MCP server to Claude.
Ask. “What's my phone's battery?”

relay

05Download

Direct download

One APK.Built in the open.

Every push to main is compiled and signed by GitHub Actions and served straight from this site. The build you install is the source you can read. No store account, no tracker SDKs.

Download APK All releases

Android 10+ · signed APK · built from main by GitHub Actions

Download phonebridge.apk on the phone, or adb install -r phonebridge.apk.
Allow “install unknown apps” for your browser when Android asks. The APK is signed; updates install over the top.
Verify if you like: sha256sum -c phonebridge.apk.sha256 against the checksum published with the build.

Signing certificate · SHA‑256 c8a6e11c e0e71218 b5c3f027 3a1d4092 cdcf1c63 17acbaed 51885861 a08cfcdd Every release is signed with this key. apksigner verify --print-certs phonebridge.apk should print the same digest.