Question about Swisscom Aton CLT321

When the MT is on the base station, the headphones cannot be plugged in.
For the headset, you need a small jack plug.
I, on the other hand, use a Bluetooth headset (Plantronics).
The phone is classy, well-made and easy to use, but not at the level of smartphones you are used to (touch, ...).

It should be possible to connect a wired headset to this phone. The connection would be a 2.5mm headphone jack.