Forum Discussion
External Contacts showing up as UPN
That's the expected behavior, Exchange is the only workload that uses the primary SMTP as identifier. If anything, you should expect Teams to use the SIP address, but MS made a decision to stick to UPN.
VasilMichev I think my real preference would be something like their display name that you can already see when you message people externally in Skype. It's a shame that we're already this far along with using Teams and we're having to deal with minor inconveniences like this when those minor inconveniences were already solved in Skype.
Is there a user voice for Teams? I think this should be a proposed addition to teams.
There is, but don't hold your breath - this issue has been discussed numerous times already and I don't see anything changing on that front. https://microsoftteams.uservoice.com/