What device was the Teams user last active on?

Hello dear community.

We in development were given the challenge within the company to ask on which device (whether on a PC or mobile/smartphone) a Teams user is/was currently/most recently active.
Background information: There is an upstream routing software that distributes incoming calls to Teams users via PSTN.
Now the routing should be different for users when they are not in the office and are on the go and use MS Teams.

We have already looked at the Graph API endpoints such as:

ownDevices 
managed devices 
Registrated user

But everything wasn't productive. We have no clue in the data returned by them that we can use to determine which device a user had or found the last conversation on. On which this is active.

We are grateful for every approach. Developer know-how is available and we can also take one or two detours

Thanks 

VG
Niko