I'm pleased to note that the latest version of Signal Private Messenger for Android and iOS includes beta support for video calling as well as the ability to call phone numbers that are not in your contacts. This is great because, if say, you want to communicate privately with, say, AntiPolygraph.org, you might not want to keep our phone number (+12028102105) in your address book (and possibly have it uploaded to Google or iCloud):

https://whispersystems.org/blog/signal-video-calls-beta/

If you have an iPhone running at least iOS 7.0, you should by all means install a new, free app from Open Whisper Systems called Signal:

https://itunes.apple.com/us/app/signal-private-messenger/id874139669

Signal is compatible with RedPhone for Android, and allows you to make free, secure calls to others with Signal or RedPhone installed. As with RedPhone, calls are free because the app uses your WiFi or data connection instead of calling minutes.

In coming months, free secure texting is going to be added to Signal for iOS, and on Android, RedPhone and TextSecure will be merged and re-named Signal.

Even if you're not very concerned about the privacy of your calls, in view of the potential cost savings (especially for international calls) there's really no reason not to use Signal or RedPhone.

Here is a sample screen shot of the Signal for iOS  contacts list. The contacts lists is also able to display a sub-list of all your contacts who also have Signal installed:



This is a screen shot of a call in progress. Note the words "hockey pair." For each call, a new word pair is generated. If both parties to the call see the same word pair, they can be confident that there is no "man in the middle" intercepting the call:



This is a shot of a sample Signal for iOS call log:

If, like me, you think that your communications are none of our (or any) government's business, you might care to use two free, open source Android apps to enhance your privacy.




Open WhisperSystems' RedPhone app allows you to encrypt your phone calls to other RedPhone users. It also uses WiFi or your phone's data connection, so that secure calls to other RedPhone users don't count against your calling plan's minutes. I have used RedPhone to make free international calls. It's available in the Google Play Store here:

https://play.google.com/store/apps/details?id=org.thoughtcrime.redphone




The other app, also from Open WhisperSystems, is TextSecure, a full replacement for the default messaging system that will encrypt all your texts to other TextSecure users. All text messages on your phone are stored in an encrypted database (regardless of whether the other party is a TextSecure user), so that they are protected in the event your phone is lost or stolen. Like RedPhone, it uses WiFi or your data plan, so that SMSes -- even international ones -- sent to other TextSecure users don't count against your calling plan. It's available in the Google Play Store here:

https://play.google.com/store/apps/details?id=org.thoughtcrime.securesms

Versions of RedPhone and TextSecure for iPhone are under development.