On All Yealink WH6x Series Headsets you can change how you answer the call, please see a step by step Guide how to do this.
First click and download the Yealink USB connect page
Once the above is downloaded
Step 1. Go to device settings
Step 2. Then select Advance Settings
Step 3. Turn off "Auto Answer when undocked" (see Below)
If You do not see the Auto Answer Option then you will need to Update the Device (see Below)\
Please call us if you are having problems changing these settings on 1-888-448-5556