As far as we can tell, Level 3 holds the crown:
Cisco Internetwork Operating System Software
IOS (tm) 2500 Software (C2500-I-L), Version 11.3(9), RELEASE SOFTWARE (fc1)
Copyright (c) 1986-1999 by cisco Systems, Inc.
Compiled Tue 06-Apr-99 18:58 by dschwart
Image text-base: 0x030298C0, data-base: 0x00001000
ROM: System Bootstrap, Version 11.0(10c), SOFTWARE
BOOTFLASH: 3000 Bootstrap Software (IGS-BOOT-R), Version 11.0(10c), RELEASE SOFTWARE (fc1)
trans-sec1.Tampa1 uptime is 18 years, 41 weeks, 1 day, 12 hours, 24 minutes
System restarted by reload at 02:20:05 GMT Fri Jul 30 1999
System image file is "flash:c2500-i-l.113-9", booted via flash
Host configuration file is "/JFowler/SNMP", booted via tftp from 10.67.20.33
cisco 2500 (68030) processor (revision L) with 2048K/2048K bytes of memory.
Processor board ID 11851149, with hardware revision 00000000
X.25 software, Version 3.0.0.
2 Ethernet/IEEE 802.3 interface(s)
2 Serial network interface(s)
32K bytes of non-volatile configuration memory.
8192K bytes of processor board System flash (Read ONLY)
Configuration register is 0x2102 (will be 0x101 at next reload)
... View more