Dear HarryStottle
Thank you for your questions.
Meetings ( Voip services) with full clients (Windows, macOS, Android, iOS) are end to end encrypted.
At the moment, you can refere to TeamViewer security statement to read more about TeamViewer sessions encryption:
https://trust-static.teamviewer.com/wp-content/uploads/2017/07/TeamViewer-Security-Statement-en.pdf
For participants joining via phone, the connection is encrypted to the point where we handover the audio stream to the provider. A phone call cannot be encrypted and at this point it’s no longer in our hand.
If you want to avoid "dial in" users, you need just to set a password (meeting with password). In this case only full clients are in the meeting and all connections are fully e2e encrypted.
Best regards Joel Malemo
... View more