If your Yealink phone has Bluetooth available, you will be able to pair a Leitner Bluetooth headset to it, and basically any other one, as well! Below are the instructions for Leitner, so give it a shot!
- Press "X" button on Yealink phone to open options menu
- Select "Basic"
- Navigate down to "Bluetooth" and toggle to "On" if it isn't already set that way
- Next, click "Scan" to start searching for devices
- Now, with the headset turned off, press and hold the Bluetooth button on the Leitner charging base until it starts to flash, then let go
- Your Yealink phone should come up with a device "DECT Headset". Click "Connect" and they should get all paired up!
Have at it!