The A/V Edge Service requires the port range from 50,000 through 59,999 to be opened inbound only if you are federating with organizations running previous versions of Office Communications Server 2007.
If you will be federating with companies that run Office Communications Server 2007 and earlier, you must open this port range for both RTP/TCP and RTP/UDP, and for both inbound and outbound connections.
Otherwise, you can close these inbound ports, and leave the port range open only for outbound connections over RTP/TCP.
A publicly routable IP address is no longer needed in a site with only a single Edge Server
And remember about the NON US setting on Edge server