I've read here over and over that, before buying an eMTA, check with Comcast to verify that your local market allows customers to use their own, as some still require that you rent the unit. I've tried calling, using online chat, and I finally even stopped in at my local office. Each time, the rep (well, at least the ones who understood what I was asking--some were clueless) just referred me to http://mydeviceinfo.comcast.net/ and said that, if it's listed there, it can be provisioned. When I've tried to ask more questions, they've acted like I'm a dolt.
Can anyone here definitively report that you've tried but that your local CC market does NOT allow customer-owned eMTA's? If so, please report details.
Let's see if we can compile a list of these markets here.