I have a very strange issue that I am hoping someone can help or at least provide some direction:

I currently have lync 2010 set up in our environment and open for external users as well through the edge server.

I have one user (user A who cannot establish a lync call with one particular user we will call userB).  If userB vpn's into our network, user A can successfully make a lync call.  If user B disconnects from VPN, the call can no no longer be established.  Now comes the interesting stuff

Other people can establish a lync call with user B when user B is not  vpn'd in, and user b can call user A when not vpn'd in.

I enabled logging on the edge server and can see the 488 not acceptable here error code

Hi,

Can you take a working and non-working trace for userB and compare the call flows ? Is there anything abnormal in non-working call flow trace apart from the error above ?

Thanks

Salesh

Maybe it's a firewall issue, I recently had a similiar problem that ended up being that the internal clients could not reach the Edge server for peer to peer communication.

Check this blog out and some links show the call flow scenarios to make sure everything is the way it should be.

http://social.technet.microsoft.com/Forums/lync/en-US/45bd8bb2-1391-472d-b68a-5fda40d1f99f/lync-external-clients-cannot-call-or-share-with-lync-internal-clients#a5e34d6a-6770-4142-a711-7136824eb650