A federated call failed to establish due to a media connectivity failure where both endpoints are internal [SOLVED]

If you have trouble connecting to an external meeting or troubles with audio then there is a quick solution to this. There probably are a number of other blogs covering the same issue.

Check for an error like this in the Lync-client log file after the attempted connection has failed:

"A federated call failed to establish due to a media connectivity failure where both endpoints are internal";CalleeMediaDebug="audio:ICEWarn=0x12b,LocalSite=xxx.241.172.10:2970,LocalMR=xxx.241.171.9:3478,RemoteSite=xxx.107.64.181:53750,RemoteMR=xxx.107.79.246:57857,PortRange=1025:65000,RemoteMRTCPPort=57857,LocalLocation=2,RemoteLocation=2,FederationType=0,NetworkName=ads.customerx.,Interfaces=0x2,BaseInterface=0x2,BaseAddress=xxx.241.172.10:20862"

Quick explanation:

LocalSite= The IP-address of the computer/device the client has signed in on.

LocalMR= The IP-address of your edge server.

RemoteSite= The IP-address of the remote client.

RemoteMR= The IP-address of the remote edge server.

So what this really means is that your local edge server has no route to the clients network segment.

Type this on your local edge server in command promt:

c:\>Route print

Look for persistent routes that fits your clients IP segment.

If its not there (what is the most likely cause of your troubles) add the route with something similar to this command.

c:\>route add -P x.x.x.x.0 MASK 255.255.255.0 z.z.z.z

x.x.x.0 being the IP-address of the network where your client tries to sign in.

z.z.z.z being the default gateway for the route. 

That should quickly solve your troubles.

You need one route for all of your Lync-clients networks.