So OK, I have been told repeatedly and told others that if you have a static set of IP addresses from Comcast that you MUST use their modem (I have a SMC) and you MUST pay their $120.00 a year "extra tax" for renting the gear.
Until last month, when I called in and was talking to a tech support person who stated I could use my own modem. I must have asked him that a dozen times and had it repeated. I didn't even believe that so I hung up and called back and got another tech support person who confirmed this.
So, thinking this was a change of heart I went out and bought a Motorola SB6120 off Ebay and when it came in I called in to Comcast and tried to switch over.
And of course, was told, sorry, can't use your own modem, you have static IPs. The stupid tech support GIRL even went on to say I could get static IP's from GoDaddy and use those with my own modem!!! Yeah right, and your mother was Miss America ya byeach!!!!
I will go ahead and keep the modem for now. Maybe one day I will be talking with either a really, really smart support person who will give me the Secret Key that Unlocks the Magic Kingdom and lets me use my own modem - or I wll be talking to some other tech support byeach who thinks that IP addresses can be scattered around like candy and I can take the call through a setup and when it doesen't work rip her a new hole where the sun don't shine.
Yeah, that's the rumor but I haven't seen a Comcast employee make any official statement one way or another as to how it actually works.
My complaint here was not that they did it this way - my complaint was that two separate Comcast reps TOLD ME that they would allow it.
From a technical perspective there's no reason that route advertisements can't be generated from customer routers, and security is an excuse because with any serious effort someone with physical access to the SMC can break into it and duplicate the modem config in some malovelent computer then trash Comcast's routing tables. It would be foolish for Comcast to not filter any route traffic coming from the customer premise regardless of whether they "owned" the gear or not.
The fact is that Comcast used to turn a blind eye to customer owned gear on business lines, in fact they used to not even charge rentals for it. It would even be worth it to me to run my own gear even if I still had to pay them, since I could then get Netflow data from my router.