To provision a Yealink phone you must first log into to phones web config.

Once in the web config click on the "Settings" tab at the top of the page, then select "Auto Provision" from the left hand menu.

Once in the Auto Provision page, go to the "Server URL" field and enter the following URL:$mac

After that is complete click on the "Confirm" button to save the change. You can now provision the phone by clicking on "Autoprovision Now"

The phone may reboot, after which the settings for the phone should be in place.