I can't tell you how many times some Sametime install/update/deployment issue has been caused because a port wasn't opened somewhere between some servers. I recently ran into an issue where a customer was deploying a Sametime Proxy to their DMZ and wanted to know what ports needed to be open. We checked some obvious ports, but things still weren't quite right so I enlisted the help of my colleague, Tony Payne, who bestowed upon me a PDF titled,
Tips For Determining ports to open between WebSphere Servers 8.5.5
Wow! The tips helped me help my customer and I've since shared it with other engineers so I'm sure it's helped others. And I'm sure it can help you too!
The PDF linked above is actually a subsection of Tony's IBM Connect 2013 session titled, "Taking IBM Sametime to the Edge: Deploying a Collaborative Extranet". You can obtain the complete presentation from the socialbiz User Group here: https://ibm.biz/BdHrUA. Also be sure to check out the Ports topics in the Planning section of our Sametime product documentation at https://ibm.biz/BdXqN7.