[mr_mitm]

I had a gig for a contractor of some banks once. One of the banks was using 5.0.0.0/8 internally. I asked the guy if it doesn't lead to issues. All the time, he said. When they first came in, they just assigned each bank 1.0.0.0/8, 2.0.0.0/8, and so on. Number ten feels really lucky, he said.

[inigyou]

As long as it's strictly separated from the internet it works. The Internetwork Packet Exchange, used for cellular roaming, is a parallel global internet with its own addresses and allocation policies.

[prerok]

This story is so silly it must be true. Thank you, made me laugh out loud.