Cable Modems

Question

Rabbi- If a person has a cable modem in his house, he is able to access the internet even if he doesnt pay for the service (thats the way it works- once the cable is set up in your house, it will work forever so long as there is a modem attached. The cable companies require you to turn the modem in when you cancel for this very reason). My question is- can i attach my own modem to the cable and then cancel my "service" to the cable provider who initially installed it? I would then be able to have a cable connection to the internet without paying for it. I already own my own modem. Thanks. aryeh