I honestly, no-ulterior-motive wonder how often this happens. I mean, isn't ADSL governed by real-world written-down standards? Isn't DOCSIS an actual standard? If so, and given the absolute standardization of things like ARP, RARP, DHCP, and so on, where could the problem possibly come in? Do they scan routers and refuse to talk to ones that don't respond with the right software version numbers?
I've got comcast, and I recently bought my own cable modem because the provider given one was dropping packets.
To get it to connect at all, I needed to call them up and tell them the model number and the the MAC address (or something that seemed analogous) of the router. I had two models to choose from (fewer than usual because I needed DOCSIS 3 I think), and they made it very clear that these were the only models they would allow you to use.
(it almost goes without saying, despite using their business support, it took three or four days, most of which I was without usable internet)
I happened to pick a Motorola SB6150. What surprised me was that there was not a shred of technical information or any management screen. After the cable was installed in my house, my brand new modem was attached to the cable infrastructure and then downloaded Comcast firmware for about twenty minutes. After my modem had completely joined the Borg, only then was it allowed to offer me internet service. Sigh...
1. We do DOCSIS 2.0, be aware. 2. We will not support your third party modem (i.e. if it doesn't work on our network, there's nothing we'll do about it) 3. We do access control, and service level determination based on MAC. Fill out the silly web form with your account number and CM MAC.