A:
There are two main types of internet. DSL, which is used by old school phone companies like Att, and cable internet which is used by Time Warner, Comcast Xfinity, and a slew of smaller regional CABLE companies. This model is specifically designed to with the phone lines that the old style land lines used in the day, and some companies like ATT still use. YOU needed a DOCSIS modem, NOT a DSL modem.
Most cable internet providers give you an exact list of the modems that work with their setup. I suggest you check with your internet provide for a list of approved modems so you can avoid confusion