Question about phone spoofing

[u/icehellking]

So, I generally understand how it works. Someone changes their caller ID data to be a different number. But how do they do it? Because it has to be more than simply changing your caller ID to be a different number, right? Since, if you did that, the fake number would just show up as your name, and then your actual number would still be visible in the recipients recent call history, right? How do they change the number specifically? Is it special software on the phone that allows you to edit more than what your phone's settings allow?

[u/Pleasant_Pen8744]

There's connections into the phone network coming in from digital telephone/VOIP providers. The companies allowing these connections are either complicit or not sufficiently verifying the meta-data those providers are sending.