Port 3716: WV CSP SMS CIR — A Ghost from Mobile Messaging's First Draft

What Port 3716 Does

Port 3716 is assigned to WV CSP SMS CIR Channel — a mouthful that unpacks to: Wireless Village Client Server Protocol, SMS-based Connection Initiation Request channel.

This is not a protocol you are likely to encounter. But it has a real story.

The Wireless Village

In April 2001, Ericsson, Motorola, and Nokia announced the Wireless Village initiative — an attempt to create a universal standard for mobile instant messaging and presence.¹ The year matters: this was before smartphones, before always-on mobile data, before it was obvious how any of this would work.

The Wireless Village Client Server Protocol (WV CSP) defined how a mobile client would talk to an instant messaging server. But it faced an immediate problem: early mobile devices couldn't maintain a persistent TCP connection. Battery life, spotty coverage, and the economics of mobile data made "always connected" impossible. So if the server had a message for you, how would it know you were ready to receive it?

The answer was the Connection Initiation Request (CIR) channel. Instead of waiting for the client to check in, the server would reach out and trigger a connection. And the cheapest, most reliable way to reach a mobile device in 2001 was SMS.²

So the SMS CIR channel worked like this: when the server had a message queued for a dormant client, it would send a specially formatted SMS to that device. The SMS wasn't the message — it was a knock on the door. The client would receive it, wake up, and establish a proper data connection to retrieve the actual content. Port 3716 was where that coordination happened.

What Became of It

The Wireless Village initiative was absorbed into the Open Mobile Alliance (OMA) when that organization formed in 2002, and the protocol became OMA IMPS (Instant Messaging and Presence Service).³ OMA IMPS found some deployment, particularly in Asia, but was eventually overtaken by smartphones and always-on data connections — the conditions that made the SMS wake-up trick necessary simply stopped being universal.

Port 3716 remains in the IANA registry, assigned but nearly unused. Traffic on this port today is most likely misconfigured software, port scans, or noise.

The Registered Port Range

Port 3716 sits in the registered port range (1024–49151). This range is where IANA records assignments for specific protocols and services — not all of them active, and not all of them well-known.

Unlike the well-known ports (0–1023), registered ports do not require elevated privileges to bind on most operating systems. Any process can open a server on port 3716 without special permissions.

What Might Be Listening on This Port

In practice, almost nothing. If you see active traffic on port 3716:

• It may be a legacy mobile messaging gateway from the early 2000s
• It may be an application that chose this port arbitrarily for internal use
• It may be a port scanner or security probe

To check what is listening on this port on your own system:

# macOS and Linux
sudo lsof -i :3716

# Linux alternative
sudo ss -tlnp | grep 3716

# Windows
netstat -ano | findstr :3716

If something unexpected is listening here, that warrants investigation — not because this port is inherently dangerous, but because unexpected listeners always do.

Why Unassigned-Adjacent Ports Matter

The registered range exists so protocols have stable, predictable homes. When port 3716 was assigned, it meant any WV CSP implementation would know exactly where to send its CIR traffic. Without that coordination, every deployment would have to negotiate port numbers independently — a small chaos that multiplies across millions of devices.

The fact that most of these assignments are now dormant is not a failure of the system. Protocols die. The problems they solved get solved differently. The registry keeps the record.