We do use variable bit rate (VBR) vs. constant bit rate (CBR). The bit rate is dependent on input speech and adapts to significant network changes.
- Yes, there is a theoretical possibility that somebody could extract information from the encrypted data stream.
- As stated in the IETF document (the topic itself was highly controversial within the IETF), VBR only is a problem for short pre-recorded or repetitive speech snippets.
- The data leak due to VBR has been shown on a theoretical level with a limited vocabulary. So far, to our knowledge, there is no known attack against naturally spoken speech.
- We don’t stream pre-recorded audio messages, they are sent as binary files.
Thanks for pointing this out to us, we will consider an even more secure option in the future.