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.
I have a friend who, for a few months, had a really strange thing going on with his phone. Any time his phone was off, calls to him would be redirected to someone else. It was another person from the same city, but using a different carrier.
Me, my friend and other friends of his called both companies to report the error multiple times. All we received was scorn and disbelief. We were told, repeatedly, that it simply couldn't happen. But it did, consistently.
It felt really silly when it got to the stage where I'd call my friend, someone else picked up and I'd go "Oh, hi, it's me again". One day, it just stopped happening.
According to customer service it wasn't and they said they didn't allow it anyway to that other company's network. And hence, they didn't believe us when we said it was happening.
Back in the dim and distant past I worked Tech Support for Psion. One gloriously quiet morning our number was redirected to the house of some poor woman in South London who eventually just gave up and left her phone off the hook.
Sadly I couldn't enjoy it, as I was running late for work and mistimed my jump onto a bus, breaking my ankle ...
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.