RedPhone is made by Open Whisper Systems, a group that provides three privacy tools in communication: RedPhone, TextSecure, and Signal. TextSecure ensures privacy in text messaging, while Signal is a private calling app solely for iOS. RedPhone is available for both iOS and Android, making it quite restrictive in terms of the platforms it runs on.
How It Works
The operation of RedPhone is simple. It encrypts your voice calls end to end, and the encryption is done in such a way that even they do not have access to call information. That’s the background of things. As far as you the user are concerned, you can use the app seamlessly without being geeky. After installing, you register through your phone number, like WhatsApp and Viber do, but here, you only need to tap a button. No need to enter your name, a login name, not even passwords, or even the phone number. The system automatically registers your phone number on the server. You will be authenticated the first time through an SMS carrying a code, like in other apps. Now if you are setting up the app on a device without a SIM card, or on a virtual machine, then instead of the code-carrying SMS, you can request for an automated call to any phone of your choosing. The app then explores your device’s contact list and integrates the system. You actually cannot add contacts within the app itself. You can make to and receive calls from people using RedPhone, and no other. So your private contact needs to install and register on RedPhone too. Calls are made over Wi-Fi and eventually, your data plan should the former be unavailable.
Added Security
RedPhone provides added security at the user level. First, whenever a call comes from an insecure number, whatever it qualifies as insecure, the call is automatically rejected and transferred to voicemail. So, your private communication circle needs to be well organized. During a call, you see two words on your screen throughout the call. The other party sees them as well. At any moment, you may want to check the genuineness of your correspondent by saying the first word and prompting them to say the second. The two words are available to only you and them, and no one else in the world.
What It Costs
RedPhone is free to install and use. There is also no in-app purchases. Your only possible element of expense, therefore, remains your connectivity as the app uses solely the Internet for the calls. You pay nothing as long as you use Wi-Fi, but you need to mind your data plan consumption in case you are out of Wi-Fi coverage. You should not be using this app as a means to save on communication, although it is a VoIP app and although it does allow you to make completely free calls to your contacts. There are other better apps for free calling. This app is solely for privacy in conversation, and only to a restricted group of people. Restricted because the app is not as popular as the other key players on the market which carry users in hundreds of millions. So, the chance of having a contact using RedPhone is quite minimal, unless, as mentioned before, you set up your own private communication group and have every there register on RedPhone. The app is open-source, meaning the code is available for auditing and editing. If you are a developer, you can participate in the Open Whispers System Developer Hub, which allows you to team up with others and delve more into the project.
The Interface
The interface is very minimal, possibly too minimal for a VoIP app. It does only two main things: voice calling and securing it. It does not really bother to harness the great potential of VoIP to enrich apps and hence user experience with features. No features at all except for private calling and browsing contacts. You cannot even add a new contact in the app; it has to be extracted from your phone’s contact list.
The Downside
RedPhone is very minimal in terms of interface and features. It is also quite limited in terms of user base, such that you will not have many contacts to talk to on it. Also, you cannot make calls to users of other platforms or to landline and mobile numbers, which is nonetheless understandable given the security it offers. The call quality of the app still has to be improved. Finally, it is available only for iOS and Android.
