Call your ISP. As long as you have the MAC ADDRESS of your modem YOUR ISP will use the MODEM of YOUR CHOICE.
Your ISP need the MAC ADDRESS to be able to use the MODEM of your CHOICE.
ISP will warn you that they will not guarantee the modem since its not own by the provider.
I have been using my OWN modem (MOTOROLA SURFBOARD). My internet access is just fine.