Please confirm. As I understand from your needs, you want a static IP for your mobile data so you can remotely access your cameras?
Not sure if this is possible since mobile service providers are designed to provide dynamic IP since those connected to them are considered "mobile", thus IP address assigned would vary every time the sim connects and per cell tower you will be connected to.
Who is your mobile provider?
That is correct. I have a TPG sim (removing mobile #) that was supplied to me (by TPG) supposedly with a static ip address. However everytime I restart my modem and connect it has a different IP. I have tried ringing the help desk but keep getting transferred around from department to department and eventually end up being disconnected. I have spent most of today on hold to no avail.