Check out, http://www.vonage.com
they offer toll-free numbers on the voip platform which is cheaper compared to the ones offered by phone companies.
The setup works like this. You sign up for a toll free number in the area of your choice through their website. Anyone who calls the toll-free number is first taken to the local vo-ip gateway of the provider, say vonage.com and then routed through the internet to the place you reside and from the vo-ip gateway of your place its routed to the PSTN line of your area which terminates the call at your home phone. Another option is to avoid the PSTN way and just by having a telephone adapator(a small instrument connected to your internet line which translates the voip call into a form which could be processed by your normal telephone) to hook your existing phone into the internet to recieve voip calls.
Usually this method works out cheap as the end point PSTN route is avoided and you recieve the calls directly from the providers voip gateway. :-)