As long as your modem is DOCSIS 2.0 compatible you can order Cablemodem service and let them know you have your own equipment. They will request your MAC address, Serial Number, and Make/Model of Modem so they can send updates as needed.
I've have my own Toshiba and Linksys modem's with Comcast and Brighthouse. The entire cablemodem system is a Time Warner design, and Brighthouse used to be Time Warner markets. You should be just fine.
I hate those RCA modems they give out, the power plug alone is a POS, let alone the quality of the device itself.