Check out the improved landing page for OCS R2 downloads here:
http://technet.microsoft.com/en-us/office/ocs/bb629431.aspx
Still looking for OCS 2007 R1 downloads? OCS 2007 R1 Downloads can be accessed here:
Dino Caputo is a Teams MVP delivering Microsoft UC solutions and is a Partner at enableUC.com
He records podcasts over at https://o365eh.com on all things Microsoft Teams and M365.