What are Threema calls?

Threema calls are voice calls in brilliant voice quality that are as secure as Threema messages. Since Threema calls are end-to-end encrypted, they are tap-proof. Instead of a phone number, the Threema ID serves as unique identifier.

  • The call connection is established using Threema messages in the background; therefore, voice calls are just as trustworthy as chats, and the same verification levels apply
  • If possible, a direct connection between caller and callee is established (peer to peer) after the connection buildup
  • Calls with IDs that are not contained in the contact list are routed through the Threema server in order to obscure the IP address
  • Because a constant bit rate is used for audio encoding, no conclusions about the content can be drawn from the size of the transmitted data packets

For detailed technical information in regard to Threema calls’ security, please refer to the Cryptography Whitepaper.

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