I don't have a technical explanation for how call misrouting can happen except to observe that the endpoints are entirely reliant on the network to get this right, they don't even tell each other "Hi I'm X trying to call Y" and "Hi I'm Y answering a call from X".

On Strowger electro-mechanical exchanges one of the nice features is that a random piece of the exchange handles each dialed call. This means the human intuitive approach of "Huh, that didn't work, I'll hang up and try again" actually had a pretty good chance of success if the problem is an electrical fault or something rather than you wrote the number down incorrectly.

I did have a morning once where every call I received was for a business in a Welsh village (I live in England) and the callers were as confused as I was that they'd reached a personal mobile phone instead. The problem resolved itself before it made me annoyed rather than confused.