My Engish is not the best but i will give a try.
We have a UCM 6510 (IP:10.0.20.9) in the headquater LAN (IP:10.20.0.0/24).
We have remote offices connected with Sophos RED15 devices.
The remote office IPs are 10.20.50.0/24; 10.20.51.0/24 … 10.20.54.0/24.
All is working fine. But sometimes, some phones in the remote offices cant hear the caller.
All ports from ant to the remote offices are open.
In the UCM Package Log i see the communication is sometimes only in one direction.
My Question is:
Do the phones need any NAT settings on the Phones SIP Account Settings?
Do the Extension need NAT activated on the extension settings in the UCM?