With OOMA you get free US calling just by buying the OOMA device. You will save thousands of dollars with their VOIP service that has all of the features of a regular phone.
Since there introduction of the service they have modified their approach, there is no longer a peer to peer component. OOMA is now utilizing Traditional IP network for VoIP.
For $250 you can have base product that gives you free telephone service for life in the US.