Port 1555 sits in the registered port range (1024-49151), assigned to a protocol called LiveLAN. If you've never heard of it, that's because it died with the 1990s videoconferencing systems it was built for.
What LiveLAN Was
PictureTel LiveLAN was a videoconferencing product designed for local area networks in the mid-to-late 1990s.12 It ran on Windows 95 PCs and brought H.323-compliant videoconferencing to corporate networks using industry-standard multimedia hardware.3
The protocol operated over TCP/IP, which meant it could run on any network infrastructure that supported IP traffic—Ethernet, Fast Ethernet, FDDI, Token Ring, Frame Relay.3 It used ITU-T H.261 for video compression and included T.120-compliant data collaboration capabilities.3
LiveLAN packets could be routed without modifying existing network infrastructure. The system adapted to network congestion and kept CPU utilization low by using hardware-assisted encoding.3
Why Port 1555 Exists
In the 1990s, videoconferencing was expensive, specialized, and mostly happened in dedicated conference rooms with equipment that cost tens of thousands of dollars. PictureTel was one of the major players, reaching peak revenues of over $490 million in 1996-1997.4
LiveLAN was their attempt to bring videoconferencing to the desktop over corporate LANs. They registered port 1555 with IANA for the protocol. Polycom later acquired PictureTel and continued supporting LiveLAN for some years.1
But the protocol couldn't survive the shift to Internet-based videoconferencing. The future belonged to WebRTC, SIP, and eventually platforms like Zoom and Teams that didn't need dedicated port numbers. LiveLAN disappeared.
What Port 1555 Carries Now
Probably nothing. The LiveLAN protocol is obsolete. The software doesn't run on modern systems. The hardware is in landfills.
Port 1555 remains registered to "livelan" in IANA's database,5 but it's effectively abandoned. Some sources mention Cisco WebEx occasionally using port 1555,6 though this appears to be opportunistic use of an available port rather than an official assignment.
If you see traffic on port 1555, it's worth investigating what's actually using it.
Checking What's Listening
To see if anything is listening on port 1555 on your system:
Linux/macOS:
Windows:
If you find something listening and you're not running legacy Polycom equipment from 2005, investigate what it is.
The Registered Port Range
Port 1555 sits in the registered port range (1024-49151). These ports are assigned by IANA to specific services upon request. Unlike well-known ports (0-1023), they don't require root privileges to bind to.
The registration process exists to prevent conflicts—to ensure that when a protocol needs a port, it gets one that won't collide with someone else's use. But registration doesn't guarantee survival. Protocols die. Companies disappear. The Internet moves on.
Port 1555 is one of thousands of registered ports that still exist on paper but carry nothing in practice. A monument to a protocol that solved a problem we solved differently.
Frequently Asked Questions About Port 1555
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