Microsoft Teams is typically installed as part of the Office Suite on University computers.  It is also available for smart phones in both the iOS and Google Play stores.  Links for all can be found at https://www.microsoft.com/en-us/microsoft-teams/download-app

Calls using the Teams Phone calling service use standard campus dialing instuctions (9 for outside like, etc).  Just use the dialpad in the "Calls" section of Teams, https://www.youtube.com/watch?v=QInQPa7CGzs

International calling with Teams is the same as with UT handsets.  See the section "International Authorization Code" at https://ut.service-now.com/sp?id=ut_bs_service_detail&sys_id=0ed65c7c4ff9d200f6897bcd0210c781 to get access.