[mothered]

I plug the ISP cable into the WAN port and call them and they access it remotely on their end.

Obviously that's how ISP's provide remote access support.

I have to disagree with you here.
Maybe my brain is just wired different, but I cannot see that answer as "obvious". The answer depends a lot on where he lives, what type of infrastructure is available to him, and how it is all set up by the ISP.

I didn't say It's the only way remote access Is provided by ISPs - evidently there are many variables Involved, that's just common sense.

My post simply pertains to the configuration you've mentioned.