Grab adapter box, 3.5mm DC jack, and RJ12 cord (short round one)
1) Connect the connector cord into the back of the headset base and other end into the HEADSET jack of the Yealink phone. (this came with the headset base)
2)Connect the 3.5mm DC jack into the headset base and other end into the left hand side of the Yealink box
3)Plug the RJ12 cord into the right hand side of the Yealink box and the other end into the EXT or EHS port on the back of the Yealink phone
4)Compat on A
And that should do it! With any luck, it is a pretty easy setup, once you find the right cords.