Sometime the service provider can test the cable modem (digital filter) through the line and even update the firmware to ensure it working properly. I had a terrible time once with a cable modem, it turned out to be the funky power adapter it was using.
or could it mean i need to tell them its mac address? idk
Yeah it could be the modem has a referance number or serial number. If your using the same router the MAC address reported to the C.O would remain the same. All the service providers where I live provide cable modem so it's setup already. But thats a good point and could be the issue.
yeah, I have Cox High Speed internet, and when I purchased my modem I had to give them it's MAC Address so it could get on their network. Any time you change the modem you have to give the ISP the updated MAC Address.