You can make regular GSM calls on the Blackphone with the standard dialer app, but Blackphone includes Silent Phone for encrypted, HD clarity calls and video chats. To start using it, open the Silent Phone app by tapping on its icon.
By tapping to the left of the Silent Phone icon at the top of the app, you can open the settings drawer. Here you will see your account information, security options, and other settings specific to Silent Phone. By scrolling down in this menu, you can select a custom Ringtone, have Silent Phone play a “Dropout tone” to warn you that you’re on a slow network, and select from other options to customize the app. If you want to log out, you can do so from the Extended menu.
To place a call to another Silent Phone user, select the person you want to call from the Contacts tab. Or, if you want to call a Silent Phone user who is not yet in your contacts, tap the dial pad icon. You can then type the recipient’s Silent Phone username in at the top of the screen, and tap the Return button on your keyboard to place the call. Alternately, you can search the Silent Circle global directory (for users who have enabled public listings).Using the “Recents” tab, you can see a list of users with whom you’ve recently shared calls. Similarly, the “Speed Dial” tab can give you quick access to frequent contacts.During an active call with another Silent Phone user, you’ll see the username of the person with whom you’re speaking as well as four icons:These icons give you the option to mute your microphone; switch to a video chat; add another Silent Phone user to the call; or put the call on speaker. (Note that to switch to a video chat, both you and the person with whom you are speaking must tap the Video icon. If only you tap the Video icon, your camera will activate and the other person will see you, but you will not see anything from their camera until they tap the Video icon as well.)While you’re in an active Silent Phone call, you’ll also see a short phrase on the top right of the screen. This is called a Short Authentication String, and each person on the call should read it back to the other caller. If the two strings do not match, it indicates a possible Man-in-The-Middle (MiTM) eavesdropping attack on your call. (You can read more about Silent Phone encryption and protection against MiTM attacks here.) If you have verified that the two strings match, simply tap on the string and confirm the secure connection.
With Silent World minutes, you can also make and receive calls to and from regular landlines and mobile phones. (See a list of plans and pricing here.) If your Silent World subscription is ready to go, just place calls to regular phone numbers using the dial pad in the Silent Phone app.
More information about Silent Phone is always available at Silent Circle support.