Port forwarding and IP address

I was having issues with port forwarding and the Foscam camera. My problem was that I had attached my Belkin router to the Vonage IP phone box that was connected to the cable box. I did this because the router had not worked directly connected to the cable box. It did work connected to the Vonage port. Everything worked fine, except for port forwarding as the WAN IP was a private IP. I had to call the cable company to reset my cable box so the Belkin router would run. Then, I was able to DIRECTLY connect the Belkin to the cable box, and Vonage to the Belkin. Then, I was able to use port forwarding. So, even if the router seems to work, be sure it is attached directly to the internet source.