Like Kenyth was saying, they normally won't troubleshoot on any device not pre-approved by them. If you really know what you are doing, and never need them, then you should be fine. But if you don't.....

I don't think, however, that they can monopolize connectivity to their services, so somewhere on their website, they should have a list, or be able to provide you with a list of approved services. Keep in mind, however, that should you move again, and need to go through all of this all over again, the modem you purchased for this ISP may not be compatible with the next.

Sucks, don't it?