http://bearware.dk/

Teamtalk is a multi-platform collaboration tool using
audio, video, file sharing, and desktop sharing.
It it free and there are versions for

• Windows 7/8/10/11
• Mac OS X 10.12 (Sierra) and later
• Ubuntu 18 Linux x86_64
• Raspbian 10 Raspberry Pi armhf
• iOS 9.0 and later
• Android 5 and later (ARMv7A, ARM64, x86, x86_64)

You can connect via the MVMA AREDN network or via the internet.
Configuration samples are on
http://miamivalleymesh.com/

73, Chuck