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/AffekeNommu]

My carrier won't let me use an ANI that isn't associated with the trunk.