Threema calls impress with crystal-clear voice quality and brilliant video quality. Since they are end-to-end encrypted, they are tap-proof. Instead of a phone number, the Threema ID serves as unique identifier.
verification level 1 (red) IDs are routed through the Threema server in order to obscure the IP address (in “Settings > Secure calls” (Android) or “Settings > Threema Calls” (iOS), there’s an option to route all calls through the Threema
server)*
*) Only applies to 1:1 calls, not to group calls.
For detailed technical information in regard to Threema calls’ security, please refer to the Cryptography Whitepaper.