Use the Teams admin center
You can use the Teams admin center to configure call forward and unanswered settings, group call pickup, and call delegation for your users.
To configure immediate call forward settings:
* In the Teams admin center, go to Users > Manage users and select a user.
* On the user details page, go to the Voice tab.
* Under Call answering rules, select Be immediately forwarded, and select the appropriate call forward type and destination.
To configure simultaneous ringing, on the same page select Ring the user's devices. In the Also allow drop-down, select the appropriate simultaneous ringing setting.
To configure unanswered settings, on the same page select the appropriate setting in the If unanswered drop-down. In the Ring for this many seconds before redirecting drop-down, specify the number of seconds to wait.
The configuration of call delegation and group call pickup are integrated into the call forward and unanswered settings by selecting the appropriate type. For example, to configure that calls should also ring the user's delegates, on the same page select Call delegation under Also allow. Then add the appropriate delegates by selecting Add people and clicking Save.
Reference:
https://learn.microsoft.com/en-us/microsoftteams/user-call-settings