https://docs.microsoft.com/en-us/microsoftteams/manage-resource-accounts (English)
https://docs.microsoft.com/de-de/microsoftteams/manage-resource-accounts (Deutsch)
Assign a phone number to resource accounts
Set-CsOnlineApplicationInstance -Identity "call_queue@domain.com" -OnpremPhoneNumber +41441234567
Set-CsOnlineApplicationInstance -Identity "auto_attendant@domain.com" -OnpremPhoneNumber +41441234568
Use resource accounts CLIP for outbound calls
Grant-CsOnlineVoiceRoutingPolicy -Identity "call_queue@domain.com" -PolicyName "Nexphone Trunk"
Grant-CsOnlineVoiceRoutingPolicy -Identity "auto_attendant@domain.com" -PolicyName "Nexphone Trunk"