Totally agree with MatthiasMichl, we have a customer with a lot of Poly Trio C60 and we are struggle on which type of license assign to the accounts: teams shared device license is non sense since these devices need calendar, teams rooms basic license fights with the limit of 25. The only choice is Fx+Teams Phone Standard but it is too much for this devices.
Also I read "With CommonAreaPhoneSignIn mode get Calls app when Shared Device License is assigned to the account. Additionally, you can enable “https://learn.microsoft.com/en-us/microsoftteams/set-up-common-area-phones#step-6---set-up-advanced-calling-on-common-area-phones-optional” setting on phone device or Teams Admin Center to get People, Walkie Talkie and Voicemail apps", but from my understanding from this ms learn document https://learn.microsoft.com/en-us/microsoftteams/set-up-common-area-phones#ip-phone-policies ,if an account is licensed with Teams Shared Device license the ip phone policy is not necessary. Is it only a way to classify the device as a Common Area Phone in Teams Admin Center?