In my basement, we see what is on the other end of one of the cables to the ONT. This is the power supply for the ONT. This box also contains the backup battery for the system. If I lose power, the backup battery supposedly runs my phone and data for 4 to 6 hours. Once it dies, I have no phone or internet connection. Since we seldom have power outages (except for that August 15th thing when I was out for 23 hours), I think we'll be OK. After that, there are cell phones, then carrier pigeons!