ring-ring

A Discord bot for the SIM-equipped modem on this server.

• Forwards SMS received by ModemManager to a Discord channel
• /status shows the modem's operator, network, signal and SMS count
• /sms to text sends an SMS. It only works in the configured channel, which is private, so channel membership is the access control. The result is posted publicly in the channel as an audit trail.
• Incoming phone calls are posted to the channel with Answer/Decline buttons. Answering bridges the call into a voice channel: everyone in the channel hears the caller, and the caller hears everyone (mixed). Hang up from Discord or the phone; missed calls are marked as such.
• /call to calls a number and bridges it into the voice channel the same way. Only domestic Japanese numbers are allowed (optionally prefixed with 184/186); emergency and other short codes and international calls are blocked. A callee's voicemail counts as answered.

How it works

• Target hardware: SIMCOM SIM7600G-H, managed by ModemManager (QMI); the bot talks to ModemManager over the system D-Bus
• Calls are controlled over the modem's AT port (interface 03, which ModemManager leaves alone): RING/AT+CLCC to detect, ATA/AT+CHUP to answer and hang up, AT+CPCMREG=1 to route call audio to the USB audio port (interface 04) as 8 kHz 16-bit mono PCM. The bot resamples it to and from Discord's 48 kHz and encodes Opus with opusscript (pure JS)
• Written in TypeScript and run directly by Node.js (type stripping, no build)
• New SMS are picked up immediately via D-Bus signals; a rescan every 60 seconds catches anything that was missed
• Forwarded messages are recorded in /var/lib/ring-ring/seen.json, so a restart never sends duplicates
• On the very first start, messages already on the modem are marked as seen instead of being forwarded (set FORWARD_EXISTING=1 to forward them)

Discord setup

1. Create an application at https://discord.com/developers/applications
2. Bot tab: Reset Token and put it in DISCORD_TOKEN. No privileged intents are needed.
3. OAuth2 > URL Generator: scopes bot and applications.commands; permissions View Channel, Send Messages, Embed Links, Connect, Speak. Open the URL to invite the bot.

Installation

As the service user with sudo rights (circuitlab), from a checkout in its home:

git clone https://github.com/circuitlab/ring-ring.git ~/ring-ring
cd ~/ring-ring
sudo sh deploy/install.sh
sudo systemctl enable --now ring-ring
journalctl -u ring-ring -f

To deploy a new version:

cd ~/ring-ring && git pull && sudo sh deploy/install.sh

install.sh installs a pinned Node.js under /opt/ring-ring/node (the distribution's Node is too old for @discordjs/voice), the app and its dependencies under /opt/ring-ring, the systemd unit and a polkit rule.

The service config is /etc/ring-ring/ring-ring.env. If deploy/ring-ring.env exists (git-ignored, holds the bot token), install.sh installs it there; otherwise it installs deploy/ring-ring.env.example once and then leaves the existing config alone (edit it with sudoedit /etc/ring-ring/ring-ring.env).

After changing the code or config, run install.sh again to deploy and restart.

SIM storage

SMS are stored on the SIM, which has little room; once it is full, new SMS can no longer be received. DELETE_AFTER_FORWARD=1 (the default) deletes messages after they are forwarded, as well as the ones marked as seen on the first start. install.sh installs the polkit rule that allows this.

Development

npm install
npm run check        # type check
DISCORD_TOKEN=... DISCORD_CHANNEL_ID=... STATE_DIR=./state npm start

Deleting and sending SMS need the polkit permission, which only the service user has.