Configuring exchange URLs
http://www.mustbegeek.com/configure-external-and-internal-url-in-exchange-2013/
Accessing Lync client from non domain computer
http://lync.community.ge/post/2012/06/10/How-to-connect-lync-from-internal-network-from-nondomain-computer.aspx
Lync federation with Skype IM request form:
https://pic.lync.com/provision/Logon/Logon.aspx?rret=https%3a%2f%2fpic.lync.com%2fprovision%2fAgreementNumber.aspx
https://technet.microsoft.com/en-us/library/jj205403.aspx