Port 2974: Signal — A Name Without a Service

What Port 2974 Is

Port 2974 sits in the registered port range (1024–49151), the middle tier of the port number space. IANA lists it as assigned to a service called "Signal," registered by Wyatt Williams via an icall.com email address, for both TCP and UDP.¹

That's where the paper trail ends.

No RFC documents the protocol. No major software implements it. No forum posts troubleshoot it. The icall.com domain, which suggests some kind of Internet calling service from an earlier era, has no surviving presence connected to this port.

What "Registered" Actually Means

The registered port range exists for applications that need a stable, predictable port number but aren't universal enough to claim a well-known port (0–1023). In theory, a company or developer registers a port, ships software that uses it, and the number becomes associated with that service in practice.

In practice, the registration process has historically required little more than filling out a form. No proof of working software. No ongoing maintenance requirement. Ports get claimed and then abandoned, leaving the registry dotted with names that point to nothing.

Port 2974 is one of those. Technically assigned. Effectively empty.

What Might Actually Be on Port 2974

If you see traffic or a listening process on port 2974, it isn't the registered "Signal" service — it's whatever application on your system decided to use an available port. Common culprits:

• Ephemeral port reuse: Some operating systems assign temporary outbound connections ports from the registered range
• Custom applications: Internal tools, game servers, or development software that picked an arbitrary number
• Malware: Attackers sometimes use obscure registered ports precisely because they look less suspicious than random high numbers

How to Check What's Using It

macOS/Linux:

sudo lsof -i :2974

Windows:

netstat -ano | findstr :2974

Both commands show the process ID. Cross-reference with your process list to identify what's actually running.

Why Ghost Registrations Matter

The port number space is finite — 65,535 ports total. The registered range (1024–49151) holds ~48,000 slots. Ghost registrations like port 2974 occupy numbers that real services might need, while contributing nothing to the ecosystem.

IANA has tightened the registration process over time, requiring more documentation and justification under RFC 6335.² But the older registrations remain in the registry, artifacts of a more permissive era.