Go through below docs to get the clear understating on SME and production deployment.
http://docwiki.cisco.com/wiki/Unified_Communications_Manager_-_Session_Manager_Edition
http://docwiki.cisco.com/wiki/Unified_Communications_Manager_-_Session_Manager_Edition:_Session_Manager_Designs
http://www.cisco.com/c/en/us/products/unified-communications/unified-communications-manager-session-management-edition/index.html
regards,
-Do rate helpful posts.