free enterprise isn't it? But correct me if I'm wrong don't you have a ISP (who owns your T1 line). T1 isn't fast enough to have a full blown ISP company and I doubt your ISP will let you do that as it's not in some agreement. You would at least need a T3 line.
Well It depends on their needs and I didn't say that I'm saying it may be not abiding to your own ISP's term of use policy. Also I'll give you a heads up configuring all the seperate IPs is going to be a pain.
Well when your line is drawing bandwidth and your ISP knocks on the door asking why you should have an exuse ready see if it's in the user agreement. Also do you know how to give internet accounts to others you can't just give them a line to your T1 as that is illegal nor you split the cost. Further more you have to configure routing and configure seperate IP adresses for all your "customers".
I'm telling you to do your research before you do it. I can't tell you not to when I know nothing about your ISP. But I will tell you if they don't allow it they will not give a second thought about discontinueing your account to their internet service. This is the problem I face now with my ISP I have Windows Server 2003 but they will not let me be a server and I pay good money for them. I am thinking about doing it anyways though because I found another ISP that has faster uploads and is cheaper at the cost of slower downloads. It's yoru choice.