I got a strange issue. External users can connect to OCS without problems. When it comes to AV sessions, only users in the same local network can make av calls. We have 3 branches all connected to the internet via ADSL. All the users in these branches connect to OCS via Edge Server. There is not a problem with IM sessions but a user in branch A can only make a conference with a user in the same branch, or in other words in the same network. A user in branch A cannot call a user in branch B. Communicator says that "Call was disconnected"