Here's a memory: My old Fido-net system, running on a 386, with a single phone line. Connected to a Microcom 34Kbaud modem.

Everything is chugging on, and connects to another system further up the chain at 2 am for network traffic. Except he's on a new phone number, on a new exchange in the state. A 914 exchange. Only the phone company's updates haven't reached all of the telephone switching centers in the sate. Somehow, it was re-routed to 911 services, and I had the police and fire department at the front door responding to a 'silent call'. They went away unhappy. I wasn't very happy either.