As far as I know the Netgear 7550 is the newest modem. If you do get a new one just keep one as a back up. When you upgrade your speed they have to send a tech out to the CO that you connect to. The tech will check the card to connect to and bump the speed up from there. If you havent used the filters you may not need to, you could already have a whole house filter installed when you first started with Frontier.
