As the title implies, I am tasked with migrating our simple chat only OCS 2007 R2 system to a Lync 2013 system. We already have a Lync server up and running that we tested with and now we want to migrate the existing users to the new server. All documentation and information I can find talks about having edge servers on the existing and new environment. My question is can this be done with out edge servers? We do not currently nor do we plan on implementing access externally.