Issue :
ms-client-diagnostics: 22; reason="Call failed to
establish due to a media connectivity failure when both endpoints are
internal";CallerMediaDebug="audio:ICEWarn=0x12b,LocalSite=
Cause
This might be because of internal VLAN restrictions implemented.
Because of those rules, Users are not able to contact the VoIP device .
Resolution :
Check there is no restrictions implemented between the user
VLAN and the VoIP devices. If that could not be changed, check the MRAS server
internal IP address is reachable from both the VoIP device and the user system