Re: "Encrypted" PSTN calls?
"Only the member's leg of the call is protected"
Which is the equivalent of no protection at all.
If a call to a PSTN user is tapped at the PSTN end, the listener can still hear what both parties are saying.
I'm not saying Silent Circle calls are useless, app to app calls are no doubt secure. But the difficulty there is you can only call someone who has a compatible device and the app, and there are already plenty of solutions for secure app to app calling.
This makes me think that the model of providing Out-Circle calls as paid service is either aimed at taking money from those who are daft enough to think it's any more secure than a normal call, or at those who are too lazy to use more than one app for calls.
My point on the comparison to Lavabit is not so much that any data is at risk but more that as a service specifically providing secure communications to prevent interception, Silent Circle is likely to find itself a target of government pressure from one nation or another both legally and through more covert means to shut down.