My ISP is Verizon FIOS. I don't have a static IP. I use dyndns.com. Started with a free account then moved to pay. They have since dropped the free accounts.
You need a method to refresh your WAN address with the DNS company. As it happens the Verizon router has a default entry for dyndns.com. The router does it for me. If your router does not allow an entry you will have to run a program on your computer on a regular basis that detects the WAN address and updates your DNS company.
I started the whole thing because a co-worker coveted a watch I wore once in awhile. As a joke I set up an IP camera aimed at the watch and gave him the URL so he could look at the watch any time he wanted. I have since retired and use the capability to watch the outside of my house.