This application is for small, closed groups of people who need to communicate with each other in absolute privacy.
Some unique capabilities include:
Direct, one-to-one contact. The two users communicate directly with each other.
Completely server-less. There exists no server for either initiating, sustaining or monitoring the communication. The communication software resides exclusively in the devices themselves.
Both verbally and in writing. The written communication is like old-style telex conversation: the typed characters are transmitted one by one and appear on the correspondent's side as soon as they are typed. Both sides can type simultaneously.
No call registration. No record is held anywhere of the conducted communication.
The operating principle is quite simple: A common email account is used, where each device of the group sends its public web address. All devices having access to this mailbox can connect to each other by using this information and a custom proprietary communication protocol.
It is recommended to create a new account specifically for this application. So, the messages created by the application will not be mixed with the user's other messages. Any normal account in Gmail, Yahoo etc. is suitable.
No central server is used, so nobody except the two communicating parties knows that they are communicating. This makes encryption unnecessary.
The application runs both in iOS and Android devices.