hi... maybe i am late... but i think i can help.

you can statically map your external ip address to internal one via the gateway you are using (it is called NAT -network address translation).
you nat your internet interface (your static ip actually) to your IP Camera
and then .. you can contact the camera by contacting your external ip

Now....
your static ip is not static basically.. it will be changed if you lost your connection for a long time(disconnection or power off your gateway) and that is why you should use a dynamic dns as mentioned up.

i am using the same thing for an internal ftp server i host at home so i can grab whatever i need anywhere.