There is a couple of ways to achieve this. I hate normally pasting links without an extract, but the extract would not be sufficient to fully answer this.
Option 1: Use Notifications
Notify the Analyst when a user adds comments from the portal for an Incident or Service Request.
Notify the End User when the Analyst updates the action log from the console for an Incident or Service Request.
If you are using the Exchange connector to process emails to create
and update emails:
Notify the Analyst when an end user replies to email notifications with comments (or provides new information) for an incident or Service
Notify an End User when analysts reply to emails requesting more information (reply to assigned to user notification or analyst
notification which will be logged as Analyst comments on the Incident
or Service Request)
We will modify assignment/re-assignment management pack to notify for assignment or re-assignment of a Service Request.
Option 2: Use third party tool
Option 1 in my own opinion is a better option.