Won't my "broadband" cable service provider charge me MORE if I have a home network/lan?
or is their charging similar to the phone company, pay a monthly fee, and if you have one wired phone great, if you have ten wired phones equally great.
depends on how u want it set up, of course. if you want them all to have their own ip address (as seen from the outside world), then you have to pay for that. (like having several phone numbers.) but otherwise, you'd probably have your own private network inside, and your firewall/router would do the address translation so that they can all share the same external ip address.