Dear Seven,
Some of my colleagues have the same problem.
The thing is that Teams has recently replaced our entire phone system. In the configuration of the call queues, you can decide presence based routing. See Below.

In summary, Teams will send the call to the persons available. Which is a very cool feature when we think about the internal calls, video meetings, etc.
In the case of the status switching to Away after 5min working outside Teams is a really big problem. Fortunately, it is not the case for all my colleagues, but imagine if we receive external calls with everybody Away, then we could miss lots of calls, or
directly send everything to the voicemail (doesn't seem really serious to be sent several times on a voicemail during working hours).
Please find a solution for this, thanks !