JW:
Yes, you can have extensions on your system in hunt groups. Your telephone lines are basically "extensions" on Verizon's much larger "system" in their central office. They establish hunt groups for lines because otherwise, a line that's busy is simply busy and can't go anywhere. Once it's tied up with a call, unless there's hunting in place for the next call to bounce over, the caller will receive a busy signal.
I am sure that you don't have ISDN lines on your system.
I still think that checking with the local cable TV provider in your area is a viable option. You might also want to look into Vonage. While I have heard good and bad comments on Vonage service, we do have some business customers that use it.
