Need help to set up the trixbox for virtual t1

I am a small business owner, and search for the low cost but highly flexible IP based 800 service, looks like the virtual T1 ( or virtual phone line) is what I am looking for. But have question about the set up.
For trixbox servers, I guess it can accept two simultanous call by default, but not sure how to make it work for multiple concurrent call.
Need some help to figure out how to accept multiple (more than two) calls by one box / one number.

Just so you know, your question is a lot like walking into a gourmet cooking school and asking how to make your Big Mac taste better.

If you are using a SIP provider and you set up a trunk, you can have as many calls as they allow and your bandwidth can handle. I can’t really get a grasp of what exactly it is you’re wanting to know.