In most cases, yes. Since your cable modem has to be registered with your ISP to work properly, it's important to buy one that's guaranteed to be compatible. While some ISPs may let you register any cable modem, most will refuse to set one up that isn't on its approved list. Fortunately, most major cable providers in the U.S. have already "pre-approved" the cable modems from all the big manufacturers. You'll normally find this information on the packaging or on the manufacturer's website. However, if you're still not sure, you can always ask your cable provider if the modem/router you're considering will work with their network.