Hide Main Site Phone number

Here's an article that may help you:

https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0064090

That just tells me how to change the number for the main site and the name on the caller ID.  I want to know how to prevent people that don't work at the main site to have their caller ID show as if they were calling from the main site.