said by bearchaser :Also since I already have the modem, how fast can I be up and running? Can I order it and be up immediately or will I have to wait for some provisioning to take place?
An easy way to answer your own question would be to simply connect your modem to the CATV jack on the wall and see if you get sync. If you get sync, connect a PC and see if you have a public IP address (and if you get redirected to the "walled garden" page). If that happens, you can just call and order the HSI service (and possibly get your modem registered again at the same time). If not, then as rody_44 said, you may have been physically disconnected, and that will require an installer to reconnect you.