|Highly unlikely your ISP would be blocking gaming ports. |
According to that site, you can check any port by just putting it into the URL:
http://port3992.icannotconnect.com , for example, will externally check port 3992 on your machine/router ...but you need to check the CoD ports.
Also, that only checks TCP whereas most game data is transmitted w/ UDP (Although, it may still need a TCP socket for control)
so the short answer is ... uh, what?