There isn't any native way to send line status/presence information across a VoIP trunk between two CMEs.
You have a couple options though:
* Aggregate both CME sites onto the same CME router, and use a VPN concentrator at one site.
* Install UCC (Unified CallConnector) Server, and peer both CME sites to UCC. Then you can install the UCC client on the user's PCs, and their 'buddy list' will show the line states for the different sites' users.
-Steve Holl