Unfortunately, I can't give you an exact answer, but the station has a 3.5 mm jack connection as an input.
The headset itself allows a simultaneous Bluetooth connection in addition to the connection to the station.

I hope it helps anyway.

No, according to the Swisscom TV Box 5 product page, it only has an HDMI output and a network connection. To connect the headset, you need Bluetooth or a 3.5mm jack. Maybe it works via your TV/projector/monitor to which you connect the box.