Teams allows for collaboration not just across Microsoft Apps but also popular 3rd party applications such as Jira, Trello, GitHub and many others.
Design and implementation of a call plan to allow your staff to call external numbers directly from teams.
Teams allows the addition of a Teams Conferencing invite to Outlook meetings, this can be used by external organisations that do not have a Teams infrastructure.
Teams allows for the collaboration of content much like SharePoint but also with rich chat and voice features.
Have a look at SSW Rules to Better Microsoft Teams.