Worried about wire taps or spooks hacking into your phone calls? Silent Phone is a encrypted voice calling app designed to let you chat securely.

Voice and video call encryption

Silent Phone has some great calling options. It allows you to make secure video chats and protected conference calls.

As long as all the participants in a call have subscribed to use Silent Phone you can chat safe in the knowledge that you're getting end-to-end encryption to prevent calls being intercepted. Silent Circle, the service behind Silent Phone, offers an 'Out-Circle Access' plan, where you can receive calls from non-subscribers with encryption applied to your side of the call.

The standard subscription for Silent Circle Mobile is $9.95 per month, at the time of writing. This gives you access to both Silent Phone and the encrypted messaging app, Silent Text. The Out-Circle Access option will set you back $24.95 per month. There's an enterprise solution, too for businesses who want to manage multiple Silent Circle subscriptions for their employees.

Call in comfort

The Silent Phone calling options are easily accessible, and the interface has been well designed. The toolbar allows access to favorites, recent calls, contacts, and the elegant keypad.

Once you're connected to someone via Silent Phone, a message will appear to say if you are connected securely or not. You'll be shown the unique key used to deliver ZRTP peer-to-peer encryption through the app. These keywords are destroyed after every call.

There are tips for preventing wire-tapping, and a 'geek mode' that shows you all the security processes running in the background that are keeping your call safe.

The call manager in Silent Phone makes it easy to take control of your calls. The conference call interface is particularly handy. It clearly lists all the participants in the conference and whether the connection is secure or not. You can easily move out of the conference and into a private chat by dragging a name out from the list.

I was very impressed by the call quality in Silent Phone, especially given the encryption and compression that's going on behind the scenes.

A secure way to chat - if you need it

Some would argue that the subscription fees are a high price to pay for a regular person who normally just calls friends and family. However, for those who need the comfort of a secure line that cannot be hacked, Silent Phone performs the task impeccably.