Port 3590: WV CSP SMS — A Mobile Messaging Fossil

What Port 3590 Is

Port 3590 is officially registered with IANA for WV CSP SMS — the Wireless Village Client Server Protocol SMS Binding. The registration dates to August 2002, and covers both TCP and UDP.

You won't find this port doing anything on modern systems. It belongs to a protocol that lost the mobile messaging war before most smartphones existed.

The Wireless Village Story

In 2001, Ericsson, Motorola, and Nokia founded Wireless Village — a consortium with a specific goal: standardize instant messaging on mobile phones before anyone else could.¹

Their approach was the Client Server Protocol (CSP), a structured messaging protocol with three layers:

• CSP — client-to-server communication
• SSP — server-to-server federation
• CLP — command line interface

The SMS Binding on port 3590 was how CSP messages traveled when the transport was SMS rather than a data connection. In 2002, this mattered. Mobile data was expensive, unreliable, and slow. SMS was ubiquitous. The idea was sound: use the SMS network you already have to carry structured instant messages.

The WV CSP SMS specification reached version 1.1 before Wireless Village merged into the Open Mobile Alliance (OMA) in 2002.² The OMA inherited the protocol, refined it, and then watched the world move on anyway. Real-time data connections got cheap. Proprietary messaging apps arrived. Nobody needed a carrier-standard IM protocol riding on SMS.

The Registered Port Range

Port 3590 sits in the registered port range (1024–49151). These ports are assigned by IANA to specific services — not to protect them the way well-known ports (0–1023) are protected, but to document common usage and reduce conflicts.

Any process can technically bind to a registered port without special privileges on most systems. The registration is a directory entry, not a lock. Port 3590 is registered for WV CSP SMS. That doesn't mean your system is running WV CSP SMS — it almost certainly isn't.

What Might Actually Be on Port 3590

Nothing, almost always.

This port doesn't appear in common malware databases, isn't used by popular modern software, and isn't reused for anything prominent. If you see traffic on port 3590, it's worth investigating — not because this port is inherently suspicious, but because unexpected open ports always deserve a look.

How to Check What's Listening

On Linux or macOS:

ss -tlnp | grep 3590
# or
lsof -i :3590

On Windows:

netstat -ano | findstr :3590
# Then look up the PID:
tasklist | findstr <PID>

From outside the machine:

nmap -p 3590 <host>

If anything responds, identify it. A process with no clear purpose binding to a registered-but-unused port is worth understanding.

Why Unassigned and Dormant Ports Matter

The IANA port registry is a historical record as much as an operational one. Entries like port 3590 mark where the industry tried to go — the protocols it built, the standards it agreed on, the futures it imagined. Most of them didn't arrive.

Dormant registrations also serve a practical function: they signal to software developers that a port number is spoken for. Building new software that happens to use 3590 would create a naming collision with the WV CSP SMS registration, even if WV CSP SMS is effectively extinct. The reservation persists.

The 48,128 ports in the registered range hold thousands of registrations like this one: protocols from defunct consortia, standards for technologies that were superseded, port numbers that sounded like a good idea in 2002.