Quoting the documentation: "
Once you have entered your IM account information, other Rally users in your Rally subscription can contact you where ever your username appears in an owner display field in the Rally application (excluding owner edit fields). Hover over the owner field and a pop-up pane displays all IM Service Providers for the user you are contacting." (
https://help.rallydev.com/set-your-profile)For example you can test it on Track > Team Status page. However, IMHO, this communication channel is not effective. You may find the FlowDock more interesting way for collaboration.