How does Silent World (formerly Out-Circle Calling) affect the security/privacy of my calls?

Calls between a Silent Circle subscriber and a regular phone line, regardless of who initiated the call, are encrypted between the subscriber and our servers and un-encrypted between our servers and the regular phone line. This means that someone targeting the leg of the communication cycle between a Silent Phone user and our servers would not be able to listen in to the conversation. On the contrary, the leg between our servers and the regular phone line is un-encrypted, just like any other regular phone call, and therefore susceptible to eavesdropping.

Please refer to the attached image for a more visual explanation on how Silent World affects the security/privacy of a call.