From ooma's web site :
ooma's patent-pending call-routing algorithm-Distributed Termination-uses the internet to connect local calling areas throughout the United States for free instead of relying primarily on traditional phone switches, known as the PSTN (Public Switched Telephone Network). As a result, each ooma customer who maintains their landline helps grow the ooma network. ooma's call-routing technology ensures a completely transparent experience so that the ability to make and receive phone calls is not impacted when their line is in use by another ooma caller.
As an example: Let's say you want to call "Claire" in Boston. You simply pick up the phone and dial. The ooma call is routed via the internet to an ooma customer with a landline in the 617 area code (let's call her "Cassy"). Cassy's ooma device (in Boston) completes the call by acting as a gateway and routes the call from her broadband to her landline, which is used to place a free call to your friend Claire. All this is done without any interruption to Cassy's phone service. In fact, Cassy doesn't even know her landline is in use and shall still be able to make and take phone calls.
What this means ? Simple words ?
You are an ooma custmer with a land phone, attach a record machine and you may able to get some other ooma cusomter's creditcard , personal talks and other secrets !!.
Nice for a movie story thread with getting hits of a murder or some theft through recording your own phone and finally getting criminals to law. But mostly the actual may be different - some body can listen to your private talk and black mail or stole personal information ( like creidcrad, otehr secrets u say by phone )
Do you think this kind of a system worth patent ? and the security threat u want to have by subscribtion ?
From : http://www.ooma.com/learn/ooma_faq.php