This feature is available in all editions.
The Lifecycle Conversations feature allows team members, stakeholders, and others to actively collaborate about anything related to a work item. And, because they are automatically associated with a workitem, you can easily find and keep track of related discussions.
Conversations occur freely throughout the system as message threads and are visible to all participants in several areas of Lifecycle:
In the Conversations panel of the related asset
Under the Collaboration menu
Note that when viewing a conversation thread, you will see the avatars of all the people who currently follow the thread. For TeamRooms and PlanningRooms, the participants are members of the room.
Participating in a Conversation
To participate in a conversation, simply type your comments in the Conversations field, and then click Share.