He probably was serious. You and I may recognize 192.168.0.5 as a IP address that can only be used on LANs, but modems and routers are often integrated nowadays, with DHCP activated by default (and possibly pre-configured even further than that), so in-depth knowledge about networks is no longer required to install broadband internet.
At the time, it took me some time to realise that 10.x.x.x was not the only option for LAN-addresses, so I can sympathize with people who would mistake 192.168.0.5 for an internet IP address.

heyn