Here is a description of our customization/integration of Vtiger with Slack messaging app for teams.
When a new user is created in VTiger, the system automatically adds as a user in Slack.
On any record in VT, you can click to add a new slack (topic) channel, add users (now or later), click save. A link to the channel is saved on that screen for later display of the linked slack conversations. For example, on an organization screen, any user could click the button and add users that might be interested in staying In touch with what happens to that company. Users can add themselves from the slack side as well. The topic would be available looking on the slack side or looking on the vTiger side in the slack widget on the organization screen.
You can see a preview of the linked slack topic/channel in VT on screen that is linked to the channel. You can see this as a widget on summary screens.
Here are some screen shots