August 7, 2017

End-to-end encrypted voice calls are about to arrive in Threema. Soon, you will be able to make phone calls that are just as secure as Threema messages. To ensure the highest possible reliability on the feature’s official launch, Threema phone calls enter a public beta test first (Android and iOS).

If you would like to test Threema phone calls and report the bugs you encounter, please participate in the beta program.

Threema calls offer excellent voice quality, and the new functionality was implemented with utmost focus on security and data restraint:

As unique identifier, the anonymous Threema ID is used instead of a phone number; thus, less exploitable metadata is generated

Threema calls are end-to-end encrypted and are therefore tap-proof; the keys are generated on the user devices and never leave these devices

Since the connection is established using Threema messages in the background, voice calls are just as trustworthy as chats; the same verification levels apply

If possible, a direct connection between caller and callee is established (peer to peer)

Because a constant bit rate is used for audio encoding, no conclusions can be drawn from the size of data packets to the content

The voice-call functionality is based on open standards

Of course, voice calls can be completely disabled in the app. More details will be provided when the feature is officially released.