I don't know. I've only had the headset for two days. Couldn't test it yet because it came with an RJ-11 plug. Had to reorder a QD-3.5 jack.

According to adapter price, it's better to return it, and order new USB headset, for example Poly Blackwire C720-M (Cable, Skype for Business) or Poly Blackwire 5220 USB-C (Cable) will cost same as phones and adapter, and will be much better

No, it comes with a 4PCP plug. You would have to buy an additional adapter from SNOM and that would be cheaper again at the price with a normal PC headset.

The Yealink T42G has an RJ9 connector and can therefore be connected directly to the headset.