Give your AI agent a private cellular tunnel
The agentic-AI explosion has put a new kind of service on developer machines: things you want to keep on your laptop but reach from elsewhere. SIMSY USB Host turns a £20 USB modem and a SIMSY SIM into a dedicated, private network interface for that service.
Local AI is private. Reachable local AI is hard.
Engineers are running real workloads on their own hardware again — coding agents, MCP servers, local LLMs, custom tooling. Privacy and cost have flipped the cloud-default. But once you want that workstation reachable from another device, the options are bad: open a port and pray, run a VPN, or rent a cloud relay that you trust with your traffic.
SIMSY USB Host gives you a network identity dedicated to the agent. The cellular interface is the access path. Anyone without a SIMSY SIM (or a SIMSY API key, if you use the Proxy) cannot reach the service. The public internet is not in the path.
Three pieces, one private path
1. Local AI agent on a port
Run your agent locally — Ollama on :11434, an MCP server on :3000, OpenClaude on whatever port you configured. SIMSY does not care what is on the other end of the port.
2. USB modem with a SIMSY SIM
The modem appears as a network interface on your machine. SIMSY assigns it an identity. Bind your agent to that interface so it is reachable over cellular.
3. Network-level access
Two options for reaching the agent: Cellular Private LAN (other SIMSY SIMs only) or the SIMSY Proxy app (anywhere with your API key). Both keep the agent off the public internet.
What you need to get going
A USB modem typically presents itself as enxXXXXXX on Linux, enX on macOS, or a new RNDIS adapter on Windows. We do not require any custom drivers — if your OS sees the modem as a network interface, SIMSY can use it.
Bind a local agent to the SIMSY interface
Most agents bind to 127.0.0.1 by default, which keeps them on localhost. Pointing them at the cellular interface puts them on the SIMSY network instead.
1. Identify the cellular interface
# After plugging in the USB modem with a SIMSY SIM:
$ ifconfig | grep -E "(enx|en[0-9])" -A 2
en7: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST>
inet 10.42.7.1 netmask 255.255.255.0 broadcast 10.42.7.255
# That's your SIMSY-managed interface. Note the IP.2. Bind your agent to that interface
# Ollama: serve on the cellular interface $ OLLAMA_HOST=10.42.7.1:11434 ollama serve # Or any HTTP server — bind to the interface IP, not 127.0.0.1 $ python -m http.server 8080 --bind 10.42.7.1
3. Reach it from another SIMSY SIM (Cellular Private LAN)
# Both SIMs in the same Cellular Private LAN group can talk directly
$ curl http://10.42.7.1:11434/api/version
{"version":"0.6.0"}
# Default-deny stays on for everything else. No public internet route exists.4. Or reach it from anywhere via the Proxy app
# 1. Install the Proxy app, paste your SIMSY API key.
# 2. Pick the agent's SIM from the device list.
# 3. The app exposes the agent on a local port:
$ curl http://localhost:11434/api/version
{"version":"0.6.0"}
# Traffic goes API key -> SIMSY core -> the agent's SIM session.
# Never on the open internet.Real workloads on real cellular
Coding agents that touch private repos
Your local Cursor/Claude Code/Aider session stays on your machine, but you can reach it from another device through SIMSY without exposing it to the open internet.
MCP servers that run on your laptop
Bring an MCP tool server up on a USB-cellular interface and let trusted SIMSY-connected machines use it as if they were on the same LAN.
On-device LLMs
Ollama or LM Studio with a 7B model on your workstation — accessible to your phone or laptop on the road, no Tailscale, no cloud, no public exposure.
Demo environments
Show an investor or partner a working agent without spinning up cloud infra. Your laptop, a USB modem, a SIM, and the proxy app on their phone.
Try it on your own machine
Tell us what you're plugging in and we'll send a SIM, walk you through the setup, and help you wire it up to your agent.
Request a developer SIM