Signal

Connect PRX to Signal using the signal-cli daemon's JSON-RPC and SSE API for encrypted messaging in DMs and groups.

Prerequisites

• A phone number registered with Signal
• signal-cli installed and registered
• signal-cli running in daemon mode with HTTP API enabled

Quick Setup

1. Install and Register signal-cli

# Install signal-cli (see https://github.com/AsamK/signal-cli for latest)
# Register your phone number
signal-cli -u +1234567890 register
signal-cli -u +1234567890 verify <verification-code>

2. Start the signal-cli Daemon

signal-cli -u +1234567890 daemon --http localhost:8686

3. Configure

[channels_config.signal]
http_url = "http://127.0.0.1:8686"
account = "+1234567890"
allowed_from = ["+1987654321", "*"]

4. Verify

prx channel doctor signal

Configuration Reference

Field	Type	Default	Description
http_url	String	required	Base URL for the signal-cli HTTP daemon (e.g., "http://127.0.0.1:8686")
account	String	required	E.164 phone number of the signal-cli account (e.g., "+1234567890")
group_id	String	null	Filter messages by group. null = accept all (DMs and groups). "dm" = only accept DMs. Specific group ID = only that group
allowed_from	[String]	[]	Allowed sender phone numbers in E.164 format. "*" = allow all
ignore_attachments	bool	false	Skip messages that are attachment-only (no text body)
ignore_stories	bool	false	Skip incoming story messages

Features

• End-to-end encryption -- all messages are encrypted via the Signal Protocol
• DM and group support -- handle both direct messages and group conversations
• SSE event stream -- listens via Server-Sent Events at /api/v1/events for real-time delivery
• JSON-RPC sending -- sends replies via JSON-RPC at /api/v1/rpc
• Flexible group filtering -- accept all messages, DMs only, or a specific group
• Attachment handling -- optionally process or skip attachment-only messages

Limitations

• Requires signal-cli to be running as a separate daemon process
• signal-cli must be registered and verified with a valid phone number
• One signal-cli instance supports one phone number
• Group message sending requires the signal-cli account to be a member of the group
• signal-cli is a Java application with its own resource requirements

Troubleshooting

Cannot connect to signal-cli

• Verify signal-cli daemon is running: curl http://127.0.0.1:8686/api/v1/about
• Check the http_url matches the daemon's bind address and port
• Ensure no firewall rules are blocking the connection

Messages from groups are ignored

• Check the group_id filter -- if set to "dm", group messages are excluded
• If set to a specific group ID, only messages from that group are accepted
• Set group_id to null (or omit it) to accept all messages

Attachment-only messages are skipped

• This is the expected behavior when ignore_attachments = true
• Set ignore_attachments = false to process attachment-only messages