An ambitious proposition.
You have to:
Buy/rent the number(s) that people calls. This is called origination. Ideally you want both toll free and local numbers with differentiated rates. You will be delivered the traffic via VoiP.
Buy the traffic to make the actual calls, this is called termination. Again, some kind of contract with likely a second tier voip carrier.
Buy some physical PRI circuit to terminate and originate in your local area.
Buy a voice gateway for the above. Here the 2811 comes useful.
Buy the internet circuits for the VoIP traffic.
Buy a server and with SIP functionality for all the above.
Buy software for billing, settlement, general administration.
Print, distribute the cards, and promote the brand against the competition.
Pay technical, administration and customer support associates.
And very likely I may have forgotten something.
All this for something that you sell, best case, for 2c a minute whereas you pay 0.85 c.
Or 30c a minute to international mobile, bought wholesale for 15c.
Not that I want to turn you down but are you sure it is worth it ?
