use this modem with Comcast . I do not even have to call they to activate it . I just use the self-activation website and be up and run in less than 5 minute . I get this to replace a sb6121 because I want 8 downstream channel , plus the sb6121 run too hot and I have to have a fan blow on it . I be on the blast 25\/4 tier and with the sb6121 I be get 36.5 mbp down and 6.5 mbp up with Power Boost . with the dpc3008 I be get 36.1 down and 5.6 up with Power Boost . Kind of disappointing . like with the dpc3000 and dpc3010 , the dpc3008 's diagnostic screen be gimp to only show you the signal level . no channel frequency , no uptime , and no log . if Motorola can show all this information in a read-only format , why can not cisco ? another disappointment . as long as the modem work it be not that big of a deal , but detailed diagnostic information can be very helpful if you really need it . temperature wise the dpc3008 run cooler than the sb6121 and do not need a fan blow on it , so I 'll stick with it for now .