Cableone should have issued you a VOIP capable Arris modem. On the back of it you should see two phone jacks labeled "Line 1" and "Line 2". If you don't see these jacks on the back, then you need to go back to your local Cableone office and get the right modem from them or have a tech bring you one out.
You can either connect the phone to the "Line 1" jack directly and get service... or you can connect the "Line 1" jack to one of the phone jacks in your house to allow service to all of the phone jacks in your house. To allow service throughout the house, you'll need to disconnect the traditional main phone line running to the house that usually terminates in a service box on an exterior wall. A Cableone tech should have already came out to your house and disconnected it when you signed up for phone service... but I wouldn't be surprised if they didn't.