What are Threema calls?
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.
- 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*
verification level 1 (red) IDs are routed through the Threema server in order to obscure the IP address (in “Settings > Threema Calls,” there’s an option to route all calls through the Threema server)*
- 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*
- Video transmission is an option of Threema calls that can be enabled at any time during an ongoing call. Once a Threema call is established, both parties can independently enable and disable video transmission by tapping the camera icon.
- Thanks to Threema’s contact verification, Man-in-the-Middle attacks can be effectively prevented, and there’s no need to manually verify a code for the purpose of authentication
*) 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.
The following system requirements must be met by both the caller’s and the callee’s device:
- Voice calls: Threema 4.22 for Android or above on Android 4.1 or above
- Video calls: Threema 4.4 for Android or above on Android 4.4 or above
- To receive calls when Threema is in the background, Google Play Services are required.
- iPhone: Threema 3.0 for iOS or above (voice calls) or Threema 4.6 for iOS or above (video calls) on an iPhone 5s or above running on iOS 10 or above
- iPad: Threema 3.0 for iOS or above (voice calls) or Threema 4.6 for iOS or above (video calls) on an iPad Pro, an iPad Air, a 5th-generation iPad or above, or a 2nd-generation iPad Mini 2 or above running on iOS 10 or above
- iPod touch: Threema 3.0 for iOS or above (voice calls) or Threema 4.6 for iOS or above (video calls) on a 6th-generation iPod touch or later running on iOS 10 or above
Group calls require Threema 5.0 for Android or above.