Hi,
I was out of the office for a couple of days so didn't reply.
Turning of the firewall on the MacBook didn't solve the problem. We did more searching and network sniffing on the mac side though.
Results are kinda unexpected.
Lync seems to work on Windows to Windows / Windows to Windows Phone. Even in different network or on 3G/4G.
The Mac to Mac and Mac to Windows doesn't seem to work with audio/video.
When we sniffed the MacBook we've noticed that during connecting a audio/video call it's trying to connect to the local ip (eg 192.168.0.x) of the other party. We can't figure out why it's trying that because a Windows client seems to work fine.
What can be the cause of this? Wrong edge config? I know that audio/video between two clients is peer-to-peer, so I can only assume the client thinks it looking for LAN connectivity instead of WAN. But why does a Windows client work? Any clue on this?