That is because the number displayed on caller ID was not the real number that called you. Search on caller ID spoofing for an explanation of what that means.
That's not necessarily true. There are VoIP phone companies with call filtering options that can reject a call and, while doing so, play a "number out of service" to the caller. But you can still call out using the line that is supposedly "out of service" and have the caller ID number show up properly as the assigned number.
If the call filtering is set up cleverly, it can create a blacklist, a whitelist, or just a list of numbers to reject.
The upshot is that a number on a caller ID for a call you just received isn't *necessarily* spoofed just because you receive a "number out of service" message.
Another possibility is that the message could simply be a voice mail greeting recorded by a caller to make it seem like the number is out of service to encourage people to hang up before the voice mail starts recording. Those "in the know" will just wait, while everyone else will hang up.
these intellectually challenged actually came up really stupid stunt, the caller ID says: "Eat Here". Just how more obvious can you get that it is a scam from a prefix that isn't even in your state.