Thanks for the response!
I plan to get a SB5101 or 6120. I understand the speeds wont change with 12 or 15 Mbs service. However, with SB6120 I will be DOCSIS 3.0 ready. I dont know if I can find a Cisco DPC3000, or DPC3825 here in DSM. Which one of these three would you recommend?
If I get my own modem, and have to use Mediacom modem for phone, that will make two modems and a router!
May be need to have the phone modem at a different cable location.....