Yealink WH64 cannot work with Pascom softphone

Hi Pascom team,

This is Eason from Yealink.
As usual, Yealink headsets WH62 and WH63 are the certified headset devices for Pascom Softphone.
So, our customer purchased some new Yealink headsets, the WH64. But finally, they found that WH64 could not work with the Pascom softphone, but WH62 could.
So I try to find out where is different. Can someone help our customer out?

BR,
Eason