Ok, but cable provider in Germany has also no public ip adresses. So anyway check your external ip if it is public or private. With an public ipv4 adress it should be no problem to get it working, other wise you need a ipv4 gate to your cam like providers feste-ip.net provides with there fipbox.
I don't know how it is in your country, but I think there will similar solutions exists.
I don't know how it is in your country, but I think there will similar solutions exists.