2 entries are registered on port 3333. It is a registered port (1024–49151) — IANA records an assignee, but nothing stops other software from listening here, which is why the number carries more than one entry.
services registered on this number
2 transports in use
entries encrypted on the wire
1 of 2 iana-registered
| port | service | proto | category | risk | views |
|---|---|---|---|---|---|
| :3333 | Network Caller ID | TCP | Network Services | caution | 10.1k |
| :3333 | DEC Notes | TCPUDP | — | safe | 0 |
Port 3333 is commonly used for the Network Caller ID (NCID) server service, an open-source system designed to distribute caller identification info across a network. It enables sharing caller ID information from a telephony input (like a modem or VoIP gateway) to various connected devices, such as PCs or media centers, enhancing call screening and logging across networked systems.
port 3333 as Network Caller ID →DEC Notes is assigned to TCP and UDP port 3333.
port 3333 as DEC Notes →The registry says what 3333 is registered to. What is listening on it right now is decided by the host, and only the host can be asked. Each of these prints the process behind the socket.
ss -ltnp | grep ':3333\b'lsof -nP -iTCP:3333 -sTCP:LISTENnetstat -ano | findstr :3333On Linux and Windows the process name comes back with the socket; on macOS lsof needs sudo to name a process that isn't yours. Match what it prints against the 2 entries above.
A port number is not a service. Anything may listen on 3333 — what you actually met is decided by the host, not the registry. If a service is missing here, it belongs in the registry.
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